There is no discipline that will work immediately.
as others have said. If you want to pursue this now, it’s about clear and consistent boundaries and being prepared to stick to them when he gets upset - including full on tantrums.
some kids will get on board without that being too bad, some will resist it hard (and if you really go for the ‘uneaten food in the bin after 20 mins / no snacks’ approach won’t eat much.)
SO. It’s really depends on two things - what your child is like and how important this is to you.
our kids were not food orientated
yet they have fast metabolisms and without regular food could go into over hungry meltdowns (but by that point would actively refuse foods).
so only food at table, no food after 20 mins boundaries wasn’t worth the pain.
so we went with it where they were and waited.
feeding dc1 a chocolate biscuit while she watched Peppa pig to get out of an over hungry meltdown while MIL clucked her disapproval was a low.
but dinner was an hour too late for dc (MILs choice).
you can bring in boundaries when you feel they are ready. Most meals wandering about or in front of a screen at 2yrs doesn’t mean that’ll still be happening at 5, or even 3.
to me ‘ready’ would be - they do choose to sit at the table sometimes. THEN I’d bring in some boundaries having talked them through in advance with dc.
i also like changes of scene for evolving our norms. So when on holiday or coming back from - as it’s all a bit different.