User Management API - set SYSTEM ADMIN group

We used the folloing API call expecting it will add "SYSTEM ADMIM(org super admin)" right to the specified user. However, the group have been set for the user was "USER GROUP ADMIN". Is it possible to set "SYSTEM ADMIM" right via API?

GET group response:

{
    "lastPage": true,
    "result": "success",
    "groups": [
        {
            "groupId": 110767925,
            "groupName": "Admins",
            "type": "SYSADMIN_GROUP",
            "adminGroupName": "_admin_Admins",
            "memberCount": 8
        },
        {
            "groupId": 110767957,
            "groupName": "InCopy Configuration",
            "type": "PRODUCT_PROFILE",
            "adminGroupName": "_admin_InCopy Configuration",
            "memberCount": 1,
            "productName": "InCopy",
            "licenseQuota": "1"
        }
}]

POST user group:

curl --location --request POST 'https://usermanagement.adobe.io/v2/usermanagement/action/XXXXXXXXX@AdobeOrg' \
--header 'Authorization: Bearer tokenXXX' \
--header 'X-api-key: xxxxxxxxxxxxxxxxxxxxxxx' \
--header 'Content-Type: application/json' \
--data-raw '[
{
"user" : "xxx@xxx.it",
"requestID": "action_1",
"do" : [{
"add" : {
"group" : ["Admins"]
}
}]
}
]'