Represents a set of permissions that's used to grant more access to one or more users without changing their profile or reassigning profiles. You can use permission sets to grant access but not to deny access.
This type extends the Metadata metadata type and inherits its name field.
Declarative Metadata File Suffix and Directory Location
The file suffix is
permissionset. There is one file for each permission set, stored in the
permissionsets folder in the corresponding package directory.
Declarative Metadata Sample Definition
When adding or changing a permission set, you don't need to include all permissions—you only need to include the permissions you're adding or changing.
Every user may have more than one permission set, for example, that means that a user may belong to both the contract manager and the organization manager.
A sample yml definition of a permission set for the contract managers is shown below.