My son is 19 months old. We are trying to get him on to regular milk. He is resisting. Any tips pls

You may try sweetening the milk with a bit of honey or try mixing half formula half regular milk. Kids develop taste preference by this age and just don't accept if they don't like it. Try consistently may be one day he randomly drinks it. Also, try to give the milk the way he likes to drink example feeding bottle, straw, direct from cup whatever way he finds it interesting.