The only way to watch the first time, if you ACTUALLY want to watch all 9 of them, is in the order they were released.
- Star Wars, Empire Strikes Back, and Return of the Jedi were the originals, made in the late 70s/early 80s. They were extremely groundbreaking fun adventure movies at that time. The famous characters all started here (Darth Vader, Luke Skywalker, Han Solo, Princess Leia, etc)
- The Phantom Menace, Attack of the Clones, and Revenge of the Sith all came out in the late 90s/early 00s. These stories take place BEFORE the original trilogy, showing how Anakin Skywalker turned into evil Darth Vader, with mostly new characters. They attempted to fill in the backstory, but many fans thought they relied too much on weird boring interplanetary economics and geopolitics, a strange decision for what was a fun adventure series. The CGI has aged badly and the acting was extremely wooden, but some superfans enjoy these movies because of the backstory elements.
- The Force Awakens, The Last Jedi, and The Rise of Skywalker came out in the late 10s. These stories take place AFTER the original trilogy. They tried to bring the fun adventure quality back with new central characters teaming up with some of the original characters from the original trilogy. As others have said, the higher ups had no overarching plan or storyline in mind to connect all 3 movies, so a lot of it ended up not making sense. I personally enjoyed watching these in the moment, they're fun, but don't think too hard about any of it.
So like I said, just watch them in that order. If you try to bounce around too much you'll be doing yourself a disservice. The movies didn't come out in chronological order, but they were obviously meant to make sense based on the movies that came earlier. If you end up liking the movies, you can mix and match in some hodgepodge order if you feel like it.
Plus, technology changed a lot between the trilogies, just start with the oldest movies and enjoy the way the effects and graphics evolved rather than bouncing back and forth.
Don't even worry about jumping into any of the tv series until you've watched the movies. If you like them enough at that point, you'll know which direction you want to go with the tv shows.