Among the new mechanics featured in the game that push the experience well ahead of that of its predecessor, Star Wars Jedi: Survivor features a Perk system that allows you to customize Cal's abilities, making him better at certain things, such as blocking, Lightsaber throws and so on.
At the start of the game, you will only have a small number of Perk slots, something that limits your possibilities greatly. These slots, however, can be easily increased to make Cal one of the deadliest Jedi Knights of all time.
One of the easiest Perk slots upgrades to get, and one that most players won't miss even with a minimal amount of exploration, is the one that can be purchased by Zee's Shop in Pyloon's Saloon on planet Koboh. This shop, which will open at some point during the story, only accepts High Republic Datadiscs, and you will need ten of them to purchase the Perk slot upgrade.
Three additional Perk slot upgrades can be found on Planet Koboh. The first is in Harvest Ridge, and you will need to be able to call the Nekko to solve the puzzle. Open the gate to the big barn, summon one Nekko on the platform, and lift it up so that you can take the beast up and use it to reach the high ledge near the silo. The second Perk slot upgrade on Koboh can be found in the Rambler's Reach Outpost inside a building located at the edge of the town, which can be reached with the help of a Nekko. Inside the building, get through the barriers with Force Dash, and complete the navigational challenges to reach the Perk Slot upgrade. The third and final Perk Slot upgrade on Koboh is found in Derelict Dam, and you will need the Koboh Grinder to open up the path near the Meditation Point.
The final three Perk slot upgrades in Star Wars Jedi: Survivor are found on planet Jedah. The first can be found in the Path of Persistence area, right on top of the high hill with the flat top. This hill can be reached with a zipline. From Arid Flats, keep to the right until you see an opening and a high ledge. Use a Spammel to reach it, and then complete a navigational challenge with some wall running to reach the zipline. The second upgrade is found on the Path of Conviction, in the last puzzle area. The location of the upgrade can only be reached by using floating drones. The third and final Perk Slot upgrade is found on the Path of Restoration in the middle area. You will need Force Dash to reach the exact location, making this one of the latest Perk slot upgrades you can get in Star Wars Jedi: Survivor.