I don't have a clue about boys or any professional skills in education; so the following are just a few ideas that I have picked up as a parent of a teen (and temp guardian of a young adult) and from the situations of friends and family , which may or may not be helpful, and may or may not apply to your individual son:
I think it is wise to stay out of conflicts in areas where teens have all the power eg food and study. But that doesn't mean that you don't show interest, ask pertinent questions, show support and encouragement, communicate with teachers, maybe express certain expectations (carefully) that are related to effort more than achievement, facilitate calm study areas and timetables, prepare snacks etc. Sometimes just sitting down regularly at home in a quiet space yourself and doing a couple of hours of your own work consistently over the week can help them to develop good habits and give them some companionship. But ultimately, the effort has to come from him. And he needs to be aware of that too.
I think his peers and the school ethos play a huge part in this. If he is in a school where effort and academic achievement is encouraged and it's not seen as uncool to study, then that is some part of the battle won. It still depends on individual effort though. A good school will start upping demands around the age of fifteen/sixteen but some pupils, especially boys, can be late developers. How mature is your ds in the rest of his non-academic life? It's good to take that in to account as I've found that teens can be high achieving in one area and not so good in another; progress isn't always even or linear.
Teens aren't always known for their forward planning skills ! 
Something that might help is a day out or a weekend away devoted to getting him to think about his future. This might include visiting someone doing a job in an area he is showing some interest in and researching it together - even writing out in map form - the steps it takes to get there. The discussion with the adult should include the benefits of doing the job in terms of personal fulfilment, challenges overcome, independence (flat?/car?) and the skills that job requires. Maybe a few on-line college or rl university visits? Discussions with uni students you know?
You might take your DS to lunch and ask him how he sees the next five years panning out? Maybe avoid getting too bogged down in career talk but try and connect with him on a more adult-to-adult level and tell him how excited and interested you are to know what direction he is going to take his life in, and get the message across that he has the control and needs to plough his own furrow. I think adopting the position of "interested to know what you are going to come up with" is a better dynamic than "frustrated parent constantly forced to nag" ifyswim because it puts the ball in his court.
It's so hard emotionally as a parent to step back, watch them make mistakes, and let them find their own way. One of the hardest things about parenting in fact. But it is imho so much better to do this in their teens than find yourself with adult offspring who have "failed to launch" because they haven't learned to take responsibility for themselves.
One of the difficulties with modern education is that pupils can be bombarded with rules and assessments and "what they cannot do" for seven years and they forget to empower students with the skills and strategies required for them to take personal responsibility or indeed emphasise the notion that they are in charge of their own destiny,; so ram that message home. School can appear like a series of discrete, meaningless obstacles that pupils have to jump over without much personal investment. It's our job as parents to connect the dots. Talk to him about how you made your career choices, take him through it step by step. Introduce him to colleagues, friends, encourage and facilitate contacts.
Perhaps set your son a few tasks (either professional or domestic) that are slightly above his level of competence or slightly outside of his comfort zone. Duke of Edinburgh award is good for this but it could be solving a professional (logistic) task involving interacting with adults or voluntary work Involving children or the elderly or conversing in a foreign language, where your teen is put on the back foot a bit (in a safe way) and is designed to shake teens out of any "coasting" behaviour, or feeling like "they know it all", take responsibility, stretch them a bit and build confidence. Overall this can have a good effect on other areas of their life such as academics. (Difficult with a pandemic going on but worth trying!)
Also, it's worthwhile checking out, or at least discussing, how many hours your DS spends on his phone or gaming. Does he have a good life balance? Does he exercise? Is he gaming a lot or on-line when he should be sleeping? Faced with difficult challenges or difficulties sometimes it's easier for our teens to sink in to the comfort of an instantly accessible on-line life, instead of confronting RL realities i.e. their marks! I know I do this when times are stressful! I would have had difficulties with self discipline if I had had a smart phone when I studied that's for sure; with constant notifications sounding, I would have been hopeless. I don't know how teens do it now tbh, with so many distractions at their finger tips!
Something related to living on-line too much can be a certain underlying anxiety (this may not apply to your son). But some teens (often girls) find it difficult to study because they are overwhelmed or anxious or comparing themselves to ridiculously unrealistic levels of perfection that they see on-line. In this case it's helpful as a parent to model tackling tasks that are overwhelming and difficult and breaking them down piece by piece. And working on them consistently and with a positive "let's get stuck in" outlook.
And try not to betray too much anxiety (difficult though this is) around the area of academic achievement. It's such a fine line and will depend on whether they need a rocket, or a bribe, or just some steering, but ultimately you want to avoid being so anxious that they come away thinking you don't believe they are capable! Installing confidence in their capabilities is key! And of course trying to do all of the above while maintaining, most important of all, a good loving relationship!
[Lastly, this probably doesn't apply to your son if he has achieved well previously but always best to check if a student has any learning difficulties. Believe it or not, the teen boy of a friend of mine only had his dyslexia discovered when he was in difficulty with his A-levels. And because the lad was quiet and handed hwk in, his mild learning difficulty had escaped his own attention and that of his parents & teachers.]
Sorry for the essay but I found this period of life with my teen difficult to negotiate! It's really tricky! Good luck 