Game concept · Advanced Activities
Tour
The game also links it as Tours, Royal Tour, Royal Tours, Grand Tour, Grand Tours.
From the game's encyclopedia
A Grand Activity in which a Liege pays a royal visit to a collection of their Vassals to reap rewards such as Gold, Dread, Opinion, Control, and Cultural Acceptance.
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.
Tour is an entry of Crusader Kings III's in-game encyclopedia (Advanced Activities). The game explains it: "A Grand Activity in which a Liege pays a royal visit to a collection of their Vassals to reap rewards such as Gold, Dread, Opinion, Control, and Cultural Acceptance." It is part of Grand Activity. It covers Cultural Festival, Hosted Dinner, Tour the Grounds, Tour Stop, Tour Success and 4 more. The game also links it as Tours, Royal Tour, Royal Tours, Grand Tour and 1 more. 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.