[Sekiro] Your game is ready, sir.
Is there a souls game where you can level up before the first boss though?
Bloodborne if you use a Madman’s Knowledge before encountering either the Cleric Beast or Father Gascoigne, this unlocks thr Doll in The Hunters Dream.
Demon’s Souls, Dark Souls 2, Elden Ring. Even if you don’t count Demon’s Souls and Elden Ring because you meet a boss before you can level there is still DS2, which has no tutorial boss, and requires you to move through an area before fighting the first boss (which will be either Last Giant, Pursuer, Dragonrider, Old Dragon Slayer, Najka, or the Rotten if I remember correctly).
You have defined boss battles before the ability to level in both Demon’s Souls and Elden Ring but DS2 and Bloodborne both let you level before a boss fight.