I think the one of the cases where someone should be a vegetarian is if they’re a hunter. If they observe the five precepts, they would have to stop killing so they wouldn’t be able to eat any meat.
If you are living off the land, then yes, you should be a vegetarian in most cases, except when you find road kill that is perfectly good to eat.
But in general, it is not a necessary practice to comply with the precepts in Theravada Buddhism.
Its kinda like Recycling, driving an EV or going solar. You can do it if you like, and its probably a great benefit to others, but doing such does not make you any more or less of a practicing (Theravada) Buddhist.