Around 40 Kenja no Isekai Seikatsu Nikki

Forty-year-old Satoshi Osako is a top player in the VRRPG Sword and Sorceries, and he dies right after beating the final boss. He wakes up in a fantasy world as his maxed-out avatar, the Great Sage Zeros Merlin, with absurd magic and one simple goal: a quiet life. That plan lasts about five minutes. He saves Celestina, a duke's daughter who is struggling with magic, and ends up her tutor, which drags him into noble problems he never wanted. The fun is watching a middle-aged guy with godlike spells try to use common sense and restraint in a world that keeps asking him for more. There are hints that other former players might be around too, so the mystery has some teeth. It sounds like Wise Man's Grandchild if the lead had back pain and zero interest in fame, or The Aristocrat's Otherworldly Adventure with a teacher-student hook. If you liked The Great Cleric's mix of overpowered magic and low-key daily life, this looks like the same lane with an older, grumpier angle.