Checkpoint64 has a preset for Age of Empires II: Definitive Edition: it already knows where the config folder is, backs it up automatically and keeps every version. Everything this site has on Age of Empires II: Definitive Edition:
Age of Empires II: Definitive Edition
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Config file location
Windows:
%USERPROFILE%\Games\Age of Empires 2 DE -
Backup guide
Competitive games keep your progress on their servers — what's on your disk is the config. Checkpoint64 versions the settings folder for 67 games and 16 dedicated servers, so a reinstall or a file verification can't cost you your binds. Free download.