What do you mean? Right to Rule and Crossroads of the World are both content packs. Every Civ DLC except expansions is a content pack.
To add to what
@King of Prussia said:
CK3 released a DLC called "Fate of Iberia." In the accompanying patch, they added a mechanic that allows to have any region of the map caught in a "struggle," i.e., the countries of that region have special mechanics to compete in a struggle that can be resolved by a win of one side or a compromise. You can also interfere from the outside etc. But without the DLC the game has no such struggle on the map - there is no actual trigger and only the "vanilla" struggle events in the base game. Yet, modders can make full use of it - they can make a hypothetical investiture struggle in central europe with all the bells and whistles the mechanic offers without the DLC. What the DLC does is put a struggle on the map in Iberia from the start of the game and adds tons of Iberian flavored events that can appear in it. A later DLC added among other things a struggle in Persia and related flavor and events. Because the struggle mechanic is part of the base game, you don't need Fate of Iberia to enjoy the struggle in Persia.
This works similarly even in larger expansions: the accompanying patch adds things like your character being able to physically travel on the map. But without DLC and mods, the base game uses this only for few tasks (going for a hunt or on pilgrimage). Otherwise, if you travel around the map, there isn't much going to happen.The DLC then adds expeditions, tournaments, visiting others or famous landmarks etc.
So, the content comes with the DLC, the mechanic is in the base game. But any later DLC or mod can fully interact with the mechanics, regardless of the player's activated DLCs. To me, this is currently the best DLC model.
In civ terms, this would have meant that any civ introduced after a certain patch could potentially interact with the mechanics of that patch in forms of bonuses or uniques. Especially in case of civ 7 with its potentially 100 civs that have so many bonuses, traditions, and legacy paths, this seems a great opportunity to do it similarly. Otherwise, all civs released in packs aside from big expansions (if these still exist) will have traditions and bonuses that would likely mostly rely on the base mechanics only. And that would really be a shame.