1.) To find an engram to override, navigate to the mod folder on your computer and search for "engramentry". ARK\ShooterGame\Content\Mods\2240488024\Blueprints\Items\Engrams

2.) Add an entry like this to your game.ini file:
OverrideNamedEngramEntries=(EngramClassName="EngramEntry_AdminBoosterGM_C",EngramHidden=False,EngramPointsCost=0,EngramLevelRequirement=0,RemoveEngramPreReq=True)

You can find a lot of information on what the options do with a simple google search.

The spawn codes spreadsheet contains a full list of engram names.[docs.google.com]