V3 hasn't gotten bigger. I still have the original V3, and she's the same size as V3 SR1, SR2, and SAE.

It might be that some very old outfits were made before SR1, and that might cause some fit problems (when the figure is posed). But I think it's just normal poke-through. Poke through is always a problem with conforming clothing - so much so that it's addressed in the Poser manual.

Some clothing has JCMs (joint-controlled morphs) that help it fit when posed. (This tends to work better with P4 than P5.) And some have other special morphs that help with the fit. (Especially skirts, capes, and such.) But freebies tend not to have such things.

Some ways to handle poke-through:

1. As Karen said, turn body parts invisible (in the hierarchy editor).

2. Scale the items slightly. If V3's breasts are poking through, dial them a little smaller, or dial the clothing a little wider, or both.

3. Use magnets to pull the clothing into place.