Most children eat at their own pace until they're satisfied.
When my grandchildren visit we all sit at the table and socialize. The children join in the conversation and it usually takes them several minutes to eat their food....after that, they may or may not ask to be excused. They also know to put their plate next to the sink and that it's not an issue if there's still any food left left on them.
If you insist they finish before they're ready, they may actually get an upset stomach from being forced to eat hurriedly. Similarly, being forced to eat everything on their plate is detrimental. Dinnertime should be a pleasurable, stress free event.