How do I improve my reading score?

I’m currently an eleventh grade student and I’ve been practicing for the SAT for a while now. I’ve done two practice tests on Khan Academy and my R&W score was in the low 600s while my Math score was over 700. The biggest issues I’ve had with the reading portions are the materials. I am completely baffled by the content of some passages, mostly the older writings. I have no idea what the passages are trying to say half the time and by extension, I have no idea what the questions are asking. To put simply, I am a person who can barely understand The Great Gatsby. Are there any ways to improve my reading comprehension? Any feedback will be appreciated.

I am having a similar issue.

My sources say to get a tutor but as a reading teacher, I would say that the only way to become a better reader is to read. This would mean reading over a lifetime from birth to the end of time. That is probably not helpful but the low 600s are really quite good.