My daughter went through a phase of picky eating. We just made it so the food on her plate was the only option for meals. She’d have to eat it or not eat. Lucky for us she liked the veggies over anything else.
We did make a deal with her that she only need have one spoonful of everything made. If she ate everything on her plate she could have seconds of whatever she wanted. If she want to fill up on salads or beans, I’m fine with that.
A bit later we let her be involved in helping pick meals. This helped alot because she could play a part in the dinner planning and then wouldn’t have an excuse for not eating those nights.
Granted she was much older at that age but it might help with a smaller child. Sit down with them and make a list of food items. Have them rate them by “ick”, “not bad” and “yummy”. This gives you a good idea of how to plan meals and can at least try to have one “yummy” item.
I suppose you could also make a list of “fun foods to try” to see if you can find something else to add to the yummy list. Make sure to add a few odd ice cream flavours (chunky-monkey, rocky road) and a couple new sweets (butterscotch, toffee, dark chocolate) so you’re not only bombarding the kid with things like sauerkraut and pickled beet soup. Make flavours an adventure. Something fun.
Like said above, you can’t fight it. You also can’t give in. My wife’s sister was one that gave in. Her kids always had the option of eating something else for dinner if they didn’t like what was being servered. Of course the “something else” always ended up being breakfast cereal. She was shocked the day I babysat the boys (then ages 4-6) and got them to eat fried egg sandwiches for lunch. They didn’t seem interested in anything else. I asked if they ever had a fried egg sandwich and they giggled because they thought I was joking. They’d never heard of one. The sheer novelty of the sandwich made it fun and they loved them. It was a favourite of theirs for years to come.
Fried egg sandwiches might not be the best but it’s damn better than a bowl of sugar cereal.