It really depends on where you focus your effort in studying for Critical reading that will determine if you increase your score or not.
I have a flat 600 CR on the SAT. I only got 2 questions wrong for vocab and the rest were from the passages. I got nearly all vocabulary questions right. Im retaking the SAT in october, and am focusing all my effort in CR on passages because i do really well on vocabulary anyways so studying for that won’t drastically increase my score.
Find your weakness then practice that. I recommend buying the “10 Real SATs” Which is the Collegeboard study guide for the Old SAT and using it for additional practice. I don’t use the math sections, i only use it for CR. When using CR, complete only the vocab and passages since those are the same as the current SAT