Min-Maxing My TRPG Build in Another World (officially translated by JNC) And, if I remember it right, the Record of Lodoss War was based on the author's campaign.
If you want fanfics, everyone recommends https://www.fanfiction.net/s/8096183/1/Harry-Potter-and-the-Natural-20?which I don't think is all that... but I do recommend https://forums.spacebattles.com/threads/in-my-time-of-troubles-dnd-si-sorta.426130/ and its sequels/alternates, just click on the author and find all threads by them.
https://www.novelupdates.com/series...pg-is-still-the-strongest-in-the-other-world/ is old school D&D themed, even the magic system is based on the "choosing X spells of X levels per day and forgetting them after they are casted" style of D&D...