MechaPilot
Explorer
Level is a bit more obscure than class. Gaining character/class levels can easily mean gaining bonuses that are not readily apparent to others. For example, proficiency bonus and increased hit points are things that are not readily apparent to a casual observer. At first blush, my answer is that level is generally not an in-game concept in my game worlds.
However, gaining class levels also means gaining access to specific abilities. The acquisition of certain abilities is a concept in my game worlds, and that tangentially makes gaining class levels an in-game thing. For example, a cleric in my games is not considered to be fully initiated into the faith until she can use the Channel Divinity feature, a wizard is not considered to have been fully graduated from her studies (either at a formal school or as another wizard's apprentice) until she chooses an Arcane Tradition, and a fighter becomes recognized as a great warrior once she gets the Extra Attack feature.
As far as spell levels go, they are not a thing. I could see spell levels being an academic concept in the game world if I used spell slots, but I vastly prefer to use spell points. Now, spell points are sort of a concept in my games. A character's maximum spell points reflects her magical potential (sort of a magical version of a Jedi detecting how strong someone is with the force), and that's something that is detectible. It is not particularly quantifiable though, so the exact number of points has less meaning than having more or less than someone else.
However, gaining class levels also means gaining access to specific abilities. The acquisition of certain abilities is a concept in my game worlds, and that tangentially makes gaining class levels an in-game thing. For example, a cleric in my games is not considered to be fully initiated into the faith until she can use the Channel Divinity feature, a wizard is not considered to have been fully graduated from her studies (either at a formal school or as another wizard's apprentice) until she chooses an Arcane Tradition, and a fighter becomes recognized as a great warrior once she gets the Extra Attack feature.
As far as spell levels go, they are not a thing. I could see spell levels being an academic concept in the game world if I used spell slots, but I vastly prefer to use spell points. Now, spell points are sort of a concept in my games. A character's maximum spell points reflects her magical potential (sort of a magical version of a Jedi detecting how strong someone is with the force), and that's something that is detectible. It is not particularly quantifiable though, so the exact number of points has less meaning than having more or less than someone else.
