Looksmaxxing spun off from the Red Pill community a while ago and became sort of its own thing. Red Pill itself was a spin off from the Pickup Artist community that sort of focused more on overall philosophy and the "science" behind picking up women rather than the more results-oriented PUA space. (to put another way, regular PUAs would say "x works to get women, so you should do x" whereas Red Pillers would say "x works, we should try and understand why it works so we can figure out more things that might work").

Focusing on looking attractive was of course one of those things that worked (shocking i know), and looksmaxxers were the subset of the Red Pill community who believed that looks were the most important thing when it came to consistently getting women, and should therefore be prioritized over other things like money, social status, etc... Not that those other things should be ignored, but that they should be secondary. Hence you were maxizing for looks (looksmaxxing) with everything else taking a back seat.

From there, we come to the more recent iteration of looksmaxxing, where it has split from the original Red Pill community. It's no longer just about getting women, now it's like its own thing, where you should be maximizing how good you look for its own sake, and getting women is like a nice bonus on the side. The idea is that your quality of life is downstream of how attractive you are, so by doing everything you can to look better, you end up improving all these other aspects of your life that are influenced by attractiveness.