Tips to get a 3yr old to eat?

Mr

I need some ideas for how to get my 3yr old son to eat. He can be picky sometimes but I think for the most part it’s either laziness or simply disinterest in eating when he’d rather be playing. He will literally sit in front of a meal for two hours and still not finish it. I’ve tried so many things:

Making his plates smaller in case he feels overwhelmed by the amount of food I’m putting on them.

Getting to watch a show on the ipad while he eats. Not getting to watch a show while he eats.

Incentivizing with walks or a trip to the park if he eats his lunch quickly enough that we have time before nap. Ice cream for dessert or bubble bath if he eats quickly enough that we have time before bed.

Leaving him at the table until he finishes or nap/bed time rolls around.

Sitting with him until he finishes. Leaving him alone to finish when we are done with our meals.

Giving him a deadline and if he hasn’t eaten by then, taking the food away.

Feeding him by hand like a baby.

Reminding him to continue eating. Ignoring whether or not he is eating.

Giving him options to choose from for his meals so that it’s not always just what I decide to make.

Trying to get him to show Cora (little sister) how a big boy eats.

None of these have consistently made an impact. Maybe here and there but more often than not he just sits there. The only meal he reliably eats is breakfast. Lunch and dinner are a struggle and he will sit in front of them most days and simply pick at them. He has a 1yr old sister and I know he regressed with some things since she came along, and I’m okay with having to spoon feed him for a short time if he feels like he needs the attention but lately he’ll refuse to eat for me either. Most meals she out eats him and does it in 1/4 of the time that it takes him to eat. I hate to let him go to bed hungry but there’s no way he’s eating enough some nights. He’s already on the smaller side weight wise, only 28lbs and change. I worry about him getting sick and not having any body fat to sustain him.

I need ideas because I’m getting very frustrated and worried for his health!