I always found disturbing how in some regular porn sites there is pornography where the actors look underage (14-18) I'm sure that they are adult actors, but is still creepy since I can't say with confidence that this is the case
Unless you're just browsing a tube site, you probably can, since the one thing the industry is actually really, really careful about is checking the age of everyone involved in the videos that are created. NOBODY wants another Traci Lords situation. Check out "2257 laws" if you ever get a second and want to find out more.
As far as the OP, there's a difference between thinking 18 year olds are physically attractive, and having the desire to exploit the possible power dynamics of actually dating an 18 year old. So no, I don't really think it normalizes it.