I’d love to play one of the new AssCreed games, but I still haven’t plAyed the first 27 games in the series. Alas.
There's no need to. The overarching modern-day "meta story" is the most dispensable, boring and most often ignored part of the series and apart from that, each game (barring a few exceptions) are stand-alone stories in that particular time period.
On the contrary, getting used to the earlier installments might actually make you like the modern ones less ("they changed it, so it sucks" or something)
I'd recommend trying
Origins, which is a good jump-on point (it's also the shortest of the new generation games), it has Ancient Egypt, a great protagonist and a great whiff of culture and atmosphere that still probably can't be beat.
Gameplay-wise,
Valhalla is probably the most enjoyable (and the Medieval England is beautiful), but it's long af, has a rather bland protagonist and some...
questionable decisions from the development team regarding the story, cultures etc. I'm not usually the most PC-type bloke, but I admit there is something
off with that.
I have put off
Odyssey until I finish
Valhalla and
Elden Ring (and maybe until I replay RDR 1 and 2 as well) , because it feels most like the middle of the road between the two, and although it's possibly shorter than
Valhalla, feels more sprawling nonetheless. On the other hand, Kassandra is one of my favourite characters in games ever and the only reason she's overshadowed and not remembered as much is probably because that was the year of Arthur Morgan and RDR2 (no one can really compete with that).