The PlatformIO code actually just copies it from the first sdkconfig.h in the examples/ folder. The notice “DO NOT EDIT, AUTOGENERATED FILE” is just wrong, PIO will not re-generate the file on every compile once it’s there.
So there’s also no way to influence the contents of the file. If the sdkconfig.h is not there when compiling the project, it will get the default one, if yes, it will do some deprecation checks and then just use it.