OK, so really, it seems to me that it's about general mobility for you, if you're sitting more. As I said upthread, think mobility rather than flexibility. And pleeeease don't just try to touch your toes in one go if you don't have the flexibility: it's a great way to spasm your back or pull your hamstrings.
If you want to do a stretching session, you need to mobilise first - go for a walk or a run ( 20 min walk or just a short 10 minute burst of a run is enough) which literally "warms up" your body, by getting all the large muscle groups working, blood flowing, and your core temperature up (ie 'warm").
Then do some simple mobilising: swing your arms in circles, forwards & back, jump squats or burpees, swing your legs forwards and back, twist your torso - all of these quite briskly, so you keep the blood flowing and the work in your muscles. Then maybe a couple of slow spine rolls, keeping your knees bent the whole time.
Then standing stretches are nice: raise one arm over your head and kind of push into that hip, and stretch that whole side. Repeat on the other side. Or stand close to a wall, feet crossed, and put the arm furthest from the wall over your head, press it into the wall, and press your hips away - again it's a stretch all down the side of your body.
If you're sitting more, you need to stretch your hip flexors - you can find lots of YouTube guides to the standard kneeling stretch for this. Look for qualified physiotherapists' YouTube channels - they give the best functional stretches.
You probably also need to just stretch out your spine on the floor, after sitting all day - I like to lie on the floor and bring my knees to my chest , and just rock forward & back, and side to side. I also like the yoga 'happy baby" stretch after a long stint at my desk.
So nothing like the splits - just functional mobility is what you probably need.