So i just finished my platinum on this (PS5), and i have to say i haven't been this captivated by a game in a while!
The game continues the story from Yakuza 7 (Like a dragon) and the intermission game (Like a Dragon Gaiden: The Man Who Erased His Name), so in a sense this is Yakuza 8. If you're going to play Infinite wealth i would recommend playing at least the 2 games i just mentioned before it (7 was practically a reboot, it's safe to start from there).
Everything that Y7 does, this game does better, bigger and more awesome. The combined mapsize is huge, the amount of sidecontent is seriously daunting; there are 2 full-blown games inside this game, naming a full blown pokemon game with a LOT to do, and a full blown animal crossing style game, amongst the usual heaps and heaps of other side content to do.
This time however, they have gone full-out and the amount of stuff to do really is almost obscene. Where Y7 had a lot of 'empty map', with nothing going on, Y8 really has an activity or something else to see and do on every 5 steps you take in the several maps.
All of the sidequests this time have been done really well, Y7 already had some really good ones but in Y8 every single one of them has a fun or good story and none of the side quests really feel like a waste of time.
Story wise, they've done a good job, there's plenty of good plot twists, funny, sad and awesome moments during the game's main quest.
Some parts of it were a bit too over-board for me (f.e. the whole vtuber part could've been left out for all i care) but overall, it was quite nice.
Y7's story felt stronger to me than Y8's, but nonetheless i enjoyed myself while playing 8's story too.
Lastly, a word on the DLC. I wish you could review that separately because it really disappoints.
The added dungeon has some decently cool stuff in it, but overall it is way too easy. All the bosses in it just fall over and even the endboss is just a complete joke, especially compared to the ones in the base game dungeon.
NG + (i'm still playing through this to complete the game on legend difficulty) also only unlocks with the DLC, which is a highly questionable move.
The DLC really only serves one purpose, which is getting your Lvl 70 Ichiban achievement with a lot less grinding than without the DLC. The added dungeon reduces that grind from probably around 10-15 hours, down to 1-2 hours.
That said, if you're not chasing platinum (or the steam achievements) and you're not desparate to see the added dungeon (or be majorly disappointed if you do) or play NG+, just get the base version of the game!