These fit like a glove and are basically the same size diameter of the leg leveler base. I use them on my tile floor and they work great. Could easily be permanent with some adhesive or double sided tape.
https://www.amazon.com/Shepherd-Hardware-9221-Reusable-Furniture/dp/B000KKVP5O
https://www.homedepot.com/p/Shepherd-1-3-4-in-Low-Friction-Furniture-Cups-4-per-Pack-9221/202531720