Does it help if they prepare the food with you? My son is a pretty good eater but he always eats with more enthusiasm when he has helped make whatever we are eating. Or if he chose that fruit etc at the supermarket himself. He's been helping since could stand at bench ie 12 mo.
Sometime after turning two he became less enthusiastic about vege. So now he gets it mainly raw or even frozen. If we're having a really bad day the vege goes in a smoothie with some fruit.
I don't serve his dinner until he's done a reasonable job of the veges.
I put the veges out from 3pm so he has time to graze over them.
Also I give him a choice of how he wants them chopped. Cucumber can be coined, sticks, cubed or 'worms' which is with a julienne peeler thing.
He used to be a fantastic eater and has slipped down to more of a 'good' eater. I hope if I stick at it the phase will pass.
I think you have to be really resolute at this age because I know too many children who turned into long term fussy eaters at this stage.
Also, I don't make him stay at the table. I think toddlers like to graze so he comes back to his food later.
So his cereal has no milk as he nibbles at it through the morning. Along with a bowl of nuts and some grapes or an apple. Perhaps a sandwich or some of my eggs which he helps make. He wanders off to do a puzzle and then comes back. He has access to the food from when he wakes til when he goes to nursery.
I'm less concerned about his table manners etc because I think that can be corrected in a week.