Game concept · Advanced Activities
Grand Activity
The game also links it as Grand Activities.
From the game's encyclopedia
Splendid displays of wealth and magnificence, Grand Activities are by nature larger and grander than regular Activities. They may have multiple Activity Phases and offer more chances for customization in planning.
Tours provide the opportunity to visit multiple Vassals in your Realm while Tournaments offer a variety of Contests to host.
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.
Grand Activity is an entry of Crusader Kings III's in-game encyclopedia (Advanced Activities). The game explains it: "Splendid displays of wealth and magnificence, Grand Activities are by nature larger and grander than regular Activities." It is part of Activity. It covers Contest, Prize, Progress to Victory, Locales, Tour and 4 more. The game also links it as Grand Activities. Patch 1.20.1.2, from game/common/game_concepts/04_ep2_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/04_ep2_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.