Okay, so 'Isekai de Cheat' usually refers to a whole bunch of stories, but I'm gonna assume you mean the pretty standard template. The protagonist gets the classic package deal, but what's interesting is how it's almost never just the powers.
First, you've got the absolute physical stat boost. We're talking strength, speed, endurance, mana pool—all maxed out from the get-go. It makes them immune to disease, age slower, and lets them punch a dragon into next week. That's the boring part, honestly.
The real meat is the magic system cheat. They don't just learn fireball; they get 'All Magic Affinity' or 'Creation Magic' that breaks the world's logic. The protagonist can invent spells on the spot, combine elements that shouldn't mix, or even manipulate concepts like 'time' or 'death' that are supposed to be forbidden. Sometimes they get a unique skill like 'Appraisal' that sees everything's stats and secrets, which is basically a built-in wiki. The story often hinges less on the power itself and more on them hiding it from others to avoid being exploited or dissected.
Honestly, the most common 'power' they gain is actually social isolation. Being that overpowered makes genuine connection impossible, which is why so many of these stories end up being power fantasies about building a harem or a kingdom—it's an attempt to manufacture stakes and relationships the raw cheat skills erased.