It doesn't really have a 16:9 "mode", but some games can be made to render that way. A 16:9 screen doesn't actually have any more pixels than a 4:3 one; they're just shaped differently.
I mean, if you wanted to, you could build an Atari 2600 game with a 16:9 mode. 16:9 vs 4:3 is almost purely...