Oblivion Remastered modder splices Fallout 3's level-by-questing into Cyrodiil, and my virtual knees are glad
Oblivion arguably isn't really Oblivion if you're not bouncing around Cyrodiil in an effort to level up your acrobatics slightly faster. Oblivion Remastered's devs knew that, and so opted to keep the classic "level up by doing the abilities you picked" approach, with some minor tweaks to make it less frustrating.
If, however, you long to ding by being handed boatloads of XP simply from completing quests and killing NPCs by any means, a modder's got you covered. While working on fleshing out a full Fallout 4-esque settlement system for Oblivin' after midnight, MadAbormodding's decided to double down on the rads and bring Fallout 3's levelling system to Cyrodiil.