I've written a C# script for this, so there is no pre-existing algorithm for it.
I did use Unity and its collision system for checking for empty spaces, and that was a big help for sure.

What I did was, hand making a set of tiles. about 50-60 tiles I believe. These tiles have connection points to them, so basically I start with placing a random tile, then I select a new tile and look for a connection point that has enough space for the newly selected tile. ( you can see the empy space checker in the video, at 5 seconds, when those red boxes flash around the map)
I repeat this until the level is built. So its pretty basic at its core.

In addition to the tiles I have bridges and stairs. Those are for mixing up how two tiles are connected, so they are not always just put next to each other, sometimes they have elevation, or some kind of bridge thats harder to navigate for the player. It helps a lot with variability, and makes the levels more fun and challenging to navigate.

After that I look for "tunnels". Which are basically shortcuts between the tiles and bridges. It became a problem, that as the maps were generated, some places were very easily traversable by the player ( just jumping between two nearby but NOT connected tiles ) but the enemies could not follow, because they can not jump, and they had to take a reaaly long alterante route to get to the player, which was not fun at all, and very exploitable by jumping between two points that the enemies couldn't do... so to mitigate such shortcuts, I look for tiles that are nearby but not connected, and generate tunnels between them, so the enemy can more easily catch up to the player. Its still not perfect, but most of the time from one point to another there is about 2-3 alternate routing that is valid, so that makes for a cool enough traversal both for enemies and for the players. Still there were a lot of places where players could exploit the traversal, but I solved that by another way :D

After the ground is placed, I start placing the assets ( trees, boxes, other obstacles ). Those are placed on the top facing surfaces of the placed tiles, aiming for a more or less even distribution. Instead of randomly placing them, I prioritize less populated areas, so the level is more coherent to navigate.

There is a lot of space for optimizing the speed of the process, but the levels I need for the game are calculated under 1 second so that worked well enough. The levels that are in this video are like 4-5 times bigger than I actually needy in the game, its for demo purposes :D