decentralized_rule_friends_modifier_effect

decentralized_rule_friends_modifier_effect = {
	if = {
		limit = {
			dynasty ?= {
				has_dynasty_perk = fp1_adventure_legacy_5
			}
			is_ruler = yes
		}
		if = {
			limit = {
				NOT = { has_variable = decentralized_rule_perk_value } 
			}
			set_variable = {
				name = decentralized_rule_perk_value
				value = 0
			}
		}
		
		every_relation = {
			type = friend
			add_to_temporary_list = decentralized_rule_friends
		}
		every_relation = {
			type = best_friend
			add_to_temporary_list = decentralized_rule_friends
		}

		if = {
			limit = {
				exists = var:decentralized_rule_perk_value
				save_temporary_scope_as = affected_friend
				var:decentralized_rule_perk_value < decentralized_rule_max
				any_in_list = {
					list = decentralized_rule_friends
					count > scope:affected_friend.var:decentralized_rule_perk_value 
				}
			}
			add_character_modifier = {
				modifier = decentralized_rule_perk_modifier
			}
			change_variable = {
				name = decentralized_rule_perk_value
				add = 1
			}
		}	
	}
}

As written in game/common/scripted_effects/01_dlc_fp1_scripted_effects.txt.