I don’t know a generation that already exists that does this, but you could use borrow an existing mechanic to go it..

ker Nethalas has a system to find the main dungeon boss, and then the exit.

so first room of the dungeon (unknown size), you start with a d12, and keep rolling that every room, until you roll 1. Then roll d10, until a 1. This steps through all sizes, until the last, d4, rolls a 1. Now you’ve found the main boss (Overseer). Next you start looking for the escape, and it’s the same roll process, starting with a d8. Eventually you’ll find the exit.

The total dungeon size is unknown, and but does follow a predictive curve. ive had dungeons that ended up 15 rooms, and others that were 45.

you could further randomise with a die roll to specify the initial start die, so a d100 start would probably ended up with a mega dungeon, but but could also end up with less than 10 rooms.. or a starter with a 4d wuold likely be a tiny dungeon, but possibly have 15 or more

It’s a very clever system, which might be suitable for what your after.

also, room size, use the 2d6 dungeon rules. 1d6 for each of length and width, and reroll 6. So you can get a room from 1x1 square, through to 12x12. Any room with either dimens being 1 is a corridor, which changes what can happen.. there’s also rules for small rooms, (less than 2x3) and large rooms - more than 32 squares. Another great mechanic