@Wingingit15
Sorry OP - hope you don’t mind me asking a question to others as have similar age kids and keep wondering how people actually do discipline them.
Where people are saying don’t tolerate whinging about food or shouting etc - what do you actually do to stop it?
You can't physically stop them but you can adjust your reaction to make it less likely that they do it again in future.
DD is a preteen so we're getting to the awkward independent/hormone induced behaviour and she is starting to push back again but so far it has always about boundaries, expectations, routines and following through with consequences.
DD makes her own breakfast most mornings, usually just cereal or toast, and there is always yogurt and fruit available too. Some days I will offer to make a hot breakfast - pancakes, waffles, bacon sandwich, scrambled eggs etc - but it will be a straightforward yes/no choice of one option "Would you like a bacon sandwich this morning?" If yes then she will have that, if not then she can make her own as usual.
She doesn't whine about wanting sausages instead of bacon (for example) as she knows that the offer is X or Y and no amount of whining will change that. If she starts whining she gets one warning/request to stop and if she continued then there would be a consequence applied - no TV time before school, reduced tech time that evening etc - and I would totally ignore her until she spoke to me properly.
If she asks politely then I will happily switch the bacon sandwich for a sausage one (provided it is practical, so in this case that we actually have sausages and I haven't already started cooking the bacon) which reinforces that being polite and respectful will have more chance of getting her her own way whereas whining and complaining gets nothing.
The same goes when we are out of the house - ever since DD was a toddler I have always been strict about using manners and behaviour in public. To reinforce this any time we went anywhere new I would clarify expected behaviour either before we left home or immediately when we arrived before we started any activity. We worked on one or two specific things at a time so each time we were out they were the main focus (eg saying please and thank you; no shouting; waiting patiently; sharing; using cutlery instead of hands; no whining etc). Once she mastered each of the manners we would move to the next ... so if she had mastered please/thank you and we were working on not shouting, I would gently remind her if she forgot to use please/thank you but she would only get consequences for shouting. (I hope that makes sense, it's hard to explain written down)
With young kids you have to be explicit "Don't misbehave" is too general of a direction- they don't have the mental acuity to assess every behaviour in the moment to know if it is "good" or "bad" behaviour.
So, when we went out I would give her specific instructions "Remember that when we go inside we have to use our manners. What are good manners?" "Is it good manners to shout?... No, it isn't so we are going to try and remember to speak nicely and if you shout then we will have to go home as that is not good manners. OK?" Then when we went into the place I would reinforce that - if DD was getting loud I would give her a gentle reminder and if she continued then she would get a warning. If she was still shouting then I would follow through with taking her home.