Modifier
Game Rule — Plus One
domain_limit_plus_one
Game Rule — Plus One (modifier ID domain_limit_plus_one) is a named modifier in Crusader Kings III. It gives Domain Limit +1. No add_…_modifier command in common/, events/ or history/ adds it. Patch 1.20.1.2, from game/common/modifiers/00_basic_modifiers.txt.
Effects
Where the game adds it
No add_…_modifier command in common/, events/ or history/ adds it.
Source: game/common/modifiers/00_basic_modifiers.txt (line 652), the English localisation (domain_limit_plus_one, domain_limit_plus_one_desc) and every add_…_modifier / remove_…_modifier in common/, events/ and history/, Crusader Kings III 1.20.1.2.