Transmigrate to the Naruto world as a mediocre member of the Uchiha Clan, caught in the Third Shinobi World War with the Fourth Hokage yet to be chosen. Then activate the One-Click Max-Level System.
"Ding! Great Fireball Technique detected. Max level with one click."
"Ding! Shadow Clone Technique detected. Max level with one click. Multiple Shadow Clone Technique awakened."
"Ding! Sharingan maxed out with one click. Susanoo, Tsukuyomi, and Amaterasu awakened."
"You say this is Sage Mode, something only one person in ten thousand can learn?"
"Ding! Sage Mode detected. Max it out with one click?"
"Ding! Wood Release bloodline detected. Max it out with one click?"
There is no ninjutsu in this world that can't be learned. And if there is, just activate the One-Click Max-Level System again.