I will write a backstory for your dnd or ttrpg character

So, you are heading to whats probably your first serious campaing and you're nervous that your history does not include sufficient info, or maybe it is your campaing number 135 and you dont really want to spend the time and energy into writting this. No problem, I will write for you a cohesive backstory for your character based in the setting, race, class, and tone of the campaing.

How do I decide whats a good backstory? Basically I try to add a sufficient amount of bakcstory aspects, questions and characters so that they can come out naturally during the gameplay, but not so many that the backstory becames overwhelming and everyone at the table is pissed off at you because your character feels like the annoying protagonist - The sweetspot is somewhere in between 1 and 2 pages of backstory and 3 to 6 concrete things that can come up at any given time.