Got a 80mm stem with 620mm wide bars on at the moment and it’s a bit cramped (tbh bike is probably a bit small). Would getting wider bars be similar to getting a longer stem?

Ta

If you think the bike is too small anyway, wider bars will increase the chances of your knees hitting your hands on tight turns.
A longer stem would be a better way to compensate for too short a top tube.

Both cured it for me, get wider bars if you think you’re grips aren’t wider than your shoulders.