I always took the approach of putting something on the plate that I knew they would eat, so new or unfamiliar or not-very-liked food would be one portion on a plate that also contained familiar or liked or frequently eaten food. That way everybody wins. My only rule is you have to chew and swallow one mouthful of whatever it is before you say you don't like it. But we also ask the child to eat X mouthfuls before they abandon the plate (X being the child's age). My DDs quite like being able to count the mouthfuls, and it goes quicker if you load up the fork/spoon for them (especially if the issue is tiredness).

Othertimes, if there's total food refusal, it might come down to tiredness, or having eaten too much earlier. We have always provided "dessert" by way of small portion fruit+yoghurt/custard/rice pudding as that provides everyone with a graceful exit. That way the kids don't go to bed hungry and there's not a massive fight either.

And sneaky mummies "win" by providing hot and savoury or nutritious finger foods as lunch or late afternoon snacks, so that it doesn't matter how much of dinner they eat. Keeping aside a portion of each night's dinner for the following day works well for this.