In some ways rule reveals/progression is a defining feature of the "Legacy" style of board games. Generally the focus on such games isn't about rule reveals/progression, because the core idea of Legacy as a style is about board games with permanent changes that last through a story campaign of some sort, but rule reveals/progressions/rule tweaks are key storytelling tools in that style.

Some of the games are notorious for having half-empty rule books that you will eventually fill with stickers for more rules.

One particular well regarded Legacy game for it's slow, careful reveal of rules is Seafall (which is noteworthy for being the first non-licensed Legacy game by the Legacy genre's "father" who built the original Risk Legacy and has contributed to many others like Pandemic Legacy). I've got it on my shelf and have been hoping to find the right group to play it with, so I've mostly tried to avoid spoilers, but the way it was described to me is that it is a full 4X (strategy gaming acronym from videogames for Explore, Expand, Exploit, and Exterminate) that starts with only the rules for Explore and expands out from there. (And it is proper exploration with players encouraged to sharpie their discoveries to the board.)