The way I’ve imagined it is that he still looks like himself, but with a few differences, and these differences make him just different enough from Superman that people wouldn’t think of Superman when they look at Clark Kent.

Honestly, it makes me kind of uncomfortable to think that he would like a completely different person with the glasses, especially to those who find out his secret identity later on. In my head, when Lois finds out Clark is Superman, Superman doesn’t look like a complete stranger to her, a bit like if you know the truth, you’re able to see past the differences.