To be honest, I've always only offered Enfys one dinner. There are probably three things on her plate, one of which I'm sure she'll eat, and the others, well, they're toddlers aren't they and live on air LOL. If she doesn't eat anything, well, she waits until the next meal or snack time. Meal times are one of the ways toddlers assert their independence, so just keep cool and I'm sure he'll come out of it.
Does he eat fruit? Bananas? Enfys loves cherry tomatoes, grapes, oatcakes are a huge hit, I put peanut butter, cream cheese, hummus on them and she gobbles them up. Have you tried pasta in tomato sauce? I make bolognese sauce in the slow cooker, with a lot of beef in it, we have it with pasta and Enfys just eats the sauce! Will he eat toast? You can spread loads of things on toast.