Just wondering if you think kids have a shut off valve???

I have a new 12 month old who never turns down food. I start everyone with the same amounts and offer more of veggies but wonder if this kid would just keep going if I kept putting more and more out. He doesn't seem ever seem full! I don't want to over feed him, I think it's possible to teach kids to eat too much or eat just because it's there.

p.s. He is a big guy to start off with