can eclosure size damage sub?

It's not that cut and dried, I think.  Too large an enclosure for a sealed woofer would give a poor frequency response and sloppy sound, as the air volume inside the box will not work as it should to compress with the cone movement.  But if the air volume is at the larger end of the recommended sizes allowed, the cone moves easier;   that's why you hear that it would take less power to respond at the same level of volume.  When it comes to any kind of vented enclosure, a poorly designed enclosure that is too large is just as bad as a poorly designed enclosure that is too small.  Vented has to be dead-on correct any which way you look at it.

Usually, with the space confinements of car audio, too large an enclosure is rarely seen as a problem.