Game concept
Camp Upgrade
The game also links it as Camp Upgrades.
From the game's encyclopedia
Camp Upgrades are unique improvements to a Camp.
Mechanically, they are Domicile Buildings — though many represent social customs or simply areas of focus for the Camp, rather than being literal structures.
The bonuses they can confer include:
• Unlocking new Officers
• Powerful Skill buffs for Followers
• Boosting the strength of Men-at-Arms
• Unlocking actions that Landed Rulers take for granted.
When an Adventurer becomes Landed, their Camp Upgrades are liquidated and a portion refunded as Gold.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Camp Upgrade is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Camp Upgrades are unique improvements to a Camp." It is part of Domicile Building. The game also links it as Camp Upgrades. Patch 1.20.1.2, from game/common/game_concepts/07_ep3_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/07_ep3_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.