Oh ignore the holier than thou perfect parents who just have to "look" at their DC and they magically behave
as though you have not tried this...
DC2 gets very destructive sometimes, trying to snatch the pen off dc1, shouting, throwing self at me so I can’t see (or breathe!)
I guess I would try to troubleshoot this. My DC have this tendency (hence why just "not allowing it" does not work) and years of experience have taught me that generally it means one or a combination of the following.
Toddler needs more focused adult 1:1 attention at other times. Perhaps DC each need set times of focused 1:1 attention so they do not clamour at each other for it.
Toddler is bored and does not know how to self entertain. Perhaps need to do a bit of "training" where you start out doing things with them and then sort of work on disengaging more and more for longer periods until you're able to each do your own thing side by side.
Toddler has learnt that shouting and getting in everyone's way is a great way to get attention. Try to shift behaviour management from reactive/shouty to calm/ignoring with something like time out if necessary, be on constant lookout for positive things to praise, even if it makes you feel like a manic dog trainer, and proactive setting things up for success in advance (e.g. having a really clear "homework time" routine), rather than hoping to appeal to their better nature, which doesn't work v well with toddlers. (This can also be part of a wider picture where you're burnt out or otherwise struggling to meet your own needs, and the DC are playing up as a response to this).
Toddler is tired and still needs a nap, but can't get it for some reason, so becomes a PITA all afternoon. Lost cause if you can't have them nap. Do homework at another time.
Toddler is restless because they really need a good run, like a dog, at least once a day or more. Some children do. There is no fix for this other than taking them for a really good run, even if it's raining and cold. Indoor options include swimming, trampolining, soft play, some kind of mini sports class or tumble tots thing, or google "heavy work" and incorporate as many of the activities as suggested into your daily life.
Toddler is hungry/thirsty/needs a wee/poo/etc - try to pre-empt this and do a snack/drink/toilet time before homework time, or shift it to a different time e.g. after meal.