But how would they know their environments enough to fully or barely utilise their ability?

Whatever the case making a good character doesn’t just come from talking about what makes them great and adding a fat list of powers or abilities. It also comes from making them relatable, understandable and flawed in some way or many.

My character Lemon has a range of abilities such as:
– Increased strength, speed, durability etc
– Natural adaptiveness so he can adapt to varying environments or set conditions like the cold or heat with restrictions and exclusions of course.
– Proficient knowledge of all kinds of things especially martial arts due to his prolonged lifetime

But he also has many flaws such as his immortality, his relationship to those he’s cared for and those he cares for, the mental toll of all his experiences. These things while surface level and plain gives you the chance to explore it narratively as you go through their story in some way.