Can you learn to code and become senior level or more from sites alone?
It's easier for me to go through websites than books, and if I can just do this it would be a relief for me.
Do a lot of experienced people just figure things out from websites?
Nope, to be senior you have to be doing it as a job for a few years. Programming alone is several league different from working with a team. And lastly to be good at something you have to actively practice (build stuff), not just read, read, read whatever ressources you use.
Real-world software is all about developing your intuition; the more sr, the more your hunches about things are correct, leading to solutions. This can only be gained on the job.