Q.My garden bed is: 11 inches topsoil, under which are 17 inches of composting leaves. Should I add anything to it?
I don’t test the soil. I don’t use fertilizer. The plants seem to do all right. Will the leaves change the pH of the soil?

Certified GKH Gardening Expert
Unless you know exactly what kind of leaves that you used, it will be hard to say. Some leaves will drastically change the pH, while others will not change it at all.
It is best to compost the leaves before hand, though. Using fresh, uncomposted leaves can invite root rotting pathogens.
These articles will help you to properly prepare garden soil: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/best-soil-raised-garden-beds.htm
https://www.gardeningknowhow.com/composting/basics/ultimate-beginners-guide-composting.htm