Hello

Yes there exists instituitional quota to some courses of some universitities like AMU  but not all.

It depends on which course you want to take admission in. If you want to take admission via JEE in BTech then the state from where you give your 12thb oard will be considered as your domicile state. Similarly for NEET you need to have a domicile certifictae issued by a state to be called as a domicile of that state.

In NEET UP has higher cutoff ranks than most other states like West Bengal but Delhi has a higher cutoff than UP. Also, every state has their own method of giving domicile certification so you have to look for that too.

As far as SC reservation is concerned and if you are interested in NEET, having a domicile of KArnataka will probably be really helpful so checkout the details of getting Karnataka domicile. All the best!