what do the the Sekiryu Beast, and Dragon Tooth trinket do ?

[Splat ♥]

if i skip on the deluxe edition can you get them in the game by playing?

[HorzaEdeo]

you can, there's in game currency you can earn to spend in the exchange shop, which has different items available weekly, and also items available daily.
obviously because it's a limited selection each week it can take a while for what you want to turn up.
also, you have to do an in game quest before you unlock all the animus stuff
here's a guide to it all: https://www.gamesradar.com/games/assassin-s-creed/assassins-creed-shadows-projects-anomalies/

the beast is just a different mount to ride, and the trinket gives you bonuses to stats. you'll find trinkets and horses in game too