In the world of Alrest, the whole world is a sea of clouds with the massive World Tree at its center. humans live on titans, giant creatures said to be sent by the Architect to serve humans, and from titans come Blades: beings with amazing abilities used as weapons, who upon the death of their wielder lose all memory (consider grief and personhood in the light of this)... titans are dying out and humans fight over what remains. how to save such a world? and is it worth doing?
-so it's a jrpg obviously, same combat as other xenoblade games. realtime combat where you press buttons to use special attacks when they're charged. you can upgrade & customize gear in various ways, but chiefly: you fight using blades. most of them are acquired in a gacha-like minigames, for which you get tokens by defeating monsters. you make them stronger by completing their affinity charts (some sidequests, defeat monsters, go places, etc)
my favorite of the xenoblade games with a (mostly) amazing cast. At some points this game is absolutely brilliant, and at some other points... well...
Xenoblade Chronicles 2 is a game which many have - rightly - criticized. The biggest thing to criticize is how the female characters are sexualized to a ludicrous degree. there's also the character (Tora) who they gave, as a main trait, 'pervert' and suffice to say he is involved in some of the absolute worst dialogue & scenes in the game. from camera angles to designs to unfunny dialogue in a few places, this game sexualizes its female characters.
others also complain that figuring out the gameplay is difficult because of bad tutorials or that the pacing in the first chapters is awful. (which I don't agree with)

Some people also seem to find the plot too 'anime' (whatever that's supposed to mean) or find it worse than xc1 and xc3 in some way.

Rex, a young Salvager who works to support his aunt’s orphanage. What I like about him: he’s just a teenager who actually has hope for the world, which sucks in a lot of ways, but his optimism and determination not to let other people’s cynisism win is admirable – and the moment when he crumbles and falters is made all the more painful for it. Plainly put, he inspires other characters to dare hope again, to find things to love in the world again
Pyra, the mythical flame-wielding Aegis who disappeared 500 years ago, who makes a deal with Rex in chapter 1 for him to bring her to Elysium. What I like about her: she's just sweet and likeable in general but on the inside she's carrying so much sadness & trauma and I love her contrast with Mythra there, Pyra's made as a people-pleaser while Mythra tries to seem above everyone, but they're both hurt. Pyra's just such a good person
Mythra, the other (original) side of the Aegis, with a bad attitude and a past that weighs on her along with her immense and dangerous powers of light. What I like about her: this is my favorite fucking character ever, first of all, anyway she starts out life super cocky but it's all a front for how hard she's trying, trying to be good and useful and do the right thing and then some really traumatizing stuff happens (spoilers). I just love her arc, I love her more shitty personality, #girlfailure
Nia, a snarky, cynical Healer from Gormott who switches sides in chapter 1 to save Rex, but is later captured by the military and in turn saved by Rex and his friends, then joining the party with her Blade Dromarch. What I like about her: she’s rude and negative because the world has hurt her and hunted her down for years, and her arc is about accepting herself & loving herself even when the world doesn’t
-full honesty: this is my favorite xenoblade game. my favorite cast, my favorite world.
-ALSO full honesty: if you have little tolerance for sexualisation or 'anime bullshit' you will not enjoy this game
-but if you like stories about characters learning to live again. or if any of what i said above appeals to you. if you can stomach some annoying pervert dialogue and bad designs, stupid humor, anime tropes don't bother you, and you want to play a jrpg with a great cast.... maybe this could be a game for you.
-do you need to play this for context for the other games? if you want to get into the series as a whole, yes.
-but honestly, do you need to play xc1 to play 2? no. do you need to play xc2 to play 3? definitely not. do you need to play xc1 to play 3? also definitely not. but if you like lore and theory-crafting and want to play the dlc to 3, then yeah, you should play this.
-also this game literally has Mythra in it! game of the year. speaking of, there is also Torna the Golden Country, the prequel dlc to this game, which i with no reservations can say is amazing and i recommend it wholeheartedly