Yes and no. It's pretty different than the core series of 1-3. While they are all stand-alone stories, the core games are connected. X is a great game and fairly separated. The thing with this game is it's deep in systems and sub systems. It can be overwhelming at first. If you can give it some time and learn the game is rewarding. While not shallow, the others are still in-depth but much more straightforward and have a heavy story focus. X isn't story-focused and is more offline MMO. 1-3 have in depth stories and characters. Music in X I think is fantastic but it's very different than the  main series. Yes it's a good place to start as just a great open world RPG and you can see the world design is a prelude to how BOTW world was designed. Fun to explore and fun overall. No if this is your trial to see how the series is as this is different than 1-3. The combat is the one thing that is similar to the other games.

There's a reason why X is called X and didn't get a number. While all four games are RPGs, X constitutes a different branch in the IP that is its own series; or well, it will be a series once it gets a sequel. X is an open world game while 1-3 unlock new areas in typical JRPG fashion by having them tied to the story. So this is the first decision you have to make here: Would you rather play an open world game or something with a much more focused story? If it's the former, you only have one option available to you.

If it's the latter, you are looking at a series that is set up similar to the Final Fantasy series in the sense that any game can be your first one, although there are very loose story connections between the XC games. By very loose I mean that XC2 spends a few seconds of its 11 hours of cutscenes to create a clear connection to XC1. XC3's ties are a bit more pronounced, but still far from being important enough to prevent it from being your first game. So what it comes down to is... watch official trailers for each game and then pick the one that resonates most with you, because all of them are available on Switch.

Whatever you do, you should play the Switch versions. The improvements in both XC1 and XCX are so significant that the original versions are hard to recommend. Also worth keeping in mind is how massive in content all games are. A story playthrough with a healthy amount of sidequests will take you around 60 hours, delving into all the optional content pushes you past the 100 hour mark.

It's the lighting engine that does it for me in XC3, the contrasts are so much better which makes the characters easily pop up in any given scenes.

Anywho, I know it's always been a matter of taste but each game in the series have always gone through different type of overall feel in it's biomes and environmental design so something like The Leftherian Archipelagos in XC2, Vallak Mountain or Satorl Marsh at night in XC1 or Erythia Sea region in XC3 have nothing to envy to what you can have in XCX regions. Moreso it is it's freeform exploration that gives it more a purpose in this case.