Usually I can get really tight ones off by using a big breaker bar (pro special tool but you can buy them).
Or in really bad cases it's time for the 5 foot scaffold pole to extend the breaker bar.
Sometimes by positioning the bar at say ten o'clock position then applying my admittedly large weight on the end and stepping onto to the bar.
But it really comes down to gravity,
Brute force and cursing the bugger who over tightened them in the first place.
Put wheel nuts on slightly loose , drive forward and brake hard , repeat going in reverse and see if it frees them off . Usually seized on hub centre flange . I have had quite a few that needed hitting from behind with a block of wood on wheel and a heavy hammer but make sure car is properly supported .When you get the wheel off , clean up both wheel centre and hub flange and then grease with Copper grease .