Some kids don't eat much. There's nothing you can do. Just offer the one meal. Not make a battle. Sit at table and talk but not about the food. Take the focus off the food. Not try and bribe or encourage or even mention the food. Sit down, chat to him, eat your meal, and if he not eaten anything, take it away when done. Reduce snacks between meal so when it is meal time, he more likely to be hungry and eat.
He doesn't really snack either though, he'd occasionally grab maybe a cracker but he'd never finish it from what I noticed. I'll try distracting him or talk to him. Thank you for your reply! I'll let you know if it works.