Just a suggestion (and ymmv, especially if there are additional factors like allergies or autism) but this really worked for us:
Provide just one family meal every night, but always have an extremely easy and filling "safe food" available as backup for anyone who doesn't want the main dinner, eg plain bread, buttered toast, a healthy muesli type thing, and maybe an ever-stocked fruit bowl. This backup food should be the same thing every single night, and require zero thought or preparation from you.
As the parent, your line is roughly this: "this is what's for dinner, for all of us. It is my job as your parent to provide plenty of healthy, nutritious food every day, but it is totally up to you, the child, to decide how much of it you eat, because it's your body and you know how hungry you are. If you don't like this dinner, there is toast, but no other alternative."
Yes maybe one of them will eat only toast and fruit for dinner for a week. Or a month! Not a problem, they'll survive. You provided a variety of healthy dinners that entire time, and they chose how much to eat. You can also, at the point of doing the weekly food shop, take meal requests to get them involved in menu planning and gladly accept offers of help from the dc in making dinner. But once the menu is set, it is non-negotiable.
But most important of all: do not comment at all on what anyone eats, good or bad. Never say "hey well done, clean plates!", and never say "oh no, sorry you didn't like it, why don't you just try..." etc. Don't act offended if they don't like it. Don't comment on if they only eat toast for days. As long as you know the food you have offered is nourishing and well-prepared, how much of it they eat is actually none of your business. You're their parent, not their personal chef.
The trick, I found, is to remove personal emotions from the food situation. You just provide dinner, and consider your job done. It's hard because food IS emotional. But in my experience, if you can remove as much emotion and frustration from it as possible, and just make it as basic and unemotional as, for example, providing heating and shelter for your children, life really does get easier because the pressure is removed, from everyone.
And it helps to make things that can be easily converted to leftovers (freezing leftover lasagne, for example, is great because that's a future lunch sorted for someone) so the bin gets a break!