Same question.

I find it little annoying that you cant find listed blueprints for that on desc page

There you go:

Put this in your game.ini

OverrideNamedEngramEntries=(EngramClassName="EngramEntry_IndominusRexEgg_C", EngramHidden=True)
OverrideNamedEngramEntries=(EngramClassName="EngramEntry_IndominusRexEgg_AB_C", EngramHidden=false)
OverrideNamedEngramEntries=(EngramClassName="EngramEntry_IndominusRexEgg_SE_C", EngramHidden=false)
OverrideNamedEngramEntries=(EngramClassName="EngramEntry_IndominusSaddle_C", EngramHidden=false)
OverrideNamedEngramEntries=(EngramClassName="EngramEntry_IndominusRexEgg_EXT_C", EngramHidden=false)
OverrideNamedEngramEntries=(EngramClassName="EngramEntry_IndominusRexEgg_GEN_C", EngramHidden=false)
OverrideNamedEngramEntries=(EngramClassName="EngramEntry_BogIndomSkin_C", EngramHidden=false)
OverrideNamedEngramEntries=(EngramClassName="EngramEntry_SnowIndomSkin_C", EngramHidden=false)
OverrideNamedEngramEntries=(EngramClassName="EngramEntry_VolcanicIndomSkin_C", EngramHidden=false)

If you want to keep saddle and skins delete these entries.


BUT BEWARE, the moment you hide engrams that way on your server it starts to lag. This is an Ark problem it happens with vanilla engrams as well as with modded ones, the moment you start to hide them via ini it starts to lag which sucks. I had this problem on several dedicated server i hosted for me and my friends till i found the only solution to this problem which is to use
bOnlyAllowSpecifiedEngrams=True
in your game.ini and write down EVERY single engram you want to use. Sounds strange but it´s the only way you can use custom engram lists without that stupid lag.
There´s a mod out there which generates an engram list in the log file, including your mod engrams (which is where i got the indom engram entries from) it´s called
GetEngrams (Engram hider utility) - ModID: 2100040774