Can one jump into the Xenoblade world having played none of the prior games? Or should I go back and start with the Xenoblade 1 remaster.
Yes, you can definitely jump in at 3 and not feel lost.
The Switch was my first Nintendo console in decades so Xenoblade 2 was the first Xenoblade game I could play (1 wasn't yet ported). I started there and didn't feel like I was missing anything but not having played the first game. I'd say ~98% of the game progressed before any connection to the other game, the last few cutscenes in the endgame referenced stuff that I could tell were from the first game by context. But it was definitely a complete story without any prior knowledge.
From the reviews I've seen 3 will be similar. Maybe a few more hints and winks earlier in the game compared to 2 (a couple of the new characters in the trailers seem to be different versions of characters from 1/2) but the Xenoblade games are always standalone efforts that can be enjoyed without knowing the history and lore. Hell, I know people that never played XC2 but did play Torna, which was a standalone XC2 expansion prequel.
This one seems to have the strongest reviews yet and appears to combine a lot of the best elements from the first two games, so in that way it might be the best introduction to the series. But I could also get wanting to understand all the passing references and appreciate the way this might tie in the first two worlds. So it's up to you, but I'd definitely recommend the series as they're some of my favourite modern JRPG's.