restapi to add userrole to a user account

Summary:

Is there a restapi to add a append userrole to an existing user account?

I used the below api as both patch and post in both cases I am getting 401 unauthorized and api documentation says if I have HR Specialist role I can able to update useraccount but unable to do.

https://{{URL}}/hcmRestApi/resources/11.13.18.05/userAccounts/{{GUID}}/child/userAccountRoles

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24C

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