You can add custom attribute according to your requirement. An attribute set is a collection of related attributes. All custom security attributes must be part of an attribute set. Attribute sets cannot be renamed or deleted.
https://learn.microsoft.com/en-us/azure/active-directory/fundamentals/custom-security-attributes-add
Sign in to the Azure portal.
Click Azure Active Directory > Custom security attributes (Preview).
Click Add attribute set to add a new attribute set.
If Add attribute set is disabled, make sure you are assigned the Attribute Definition Administrator role
Enter a name, description, and maximum number of attributes.
An attribute set name can be 32 characters with no spaces or special characters.