I’m biased as I absolutely adore Rebels, but I wouldn’t avoid any episodes. It does have its misses here and there but pretty much every episode is important in some way, be it establishing traits of the characters or setting up something which will be utilised in some way further down the line.
And yeah, I’d say it does mature as it goes on, keeping pace with the younger viewers (like me) who grew up watching it live. It remains a kid’s show at heart, though, so as long as you’re not expecting any Andor-level storylines you should be able to appreciate it for what it is.