Setting Unified Group properties via API

You can do that with Microsoft Graph only at creation time. I'm disabling the member notification on group adding like this:

Like this:

Url: https://graph.microsoft.com/v1.0/groups

Request Body:

--

{
    "displayName": "TestGroup-01",
    "groupTypes": [
        "Unified"
    ],
    "mailEnabled": true,
    "mailNickname": "testgroup-01",
    "resourceBehaviorOptions": [
        "WelcomeEmailDisabled"
    ],
    "securityEnabled": false,
    "visibility": "Private",
}

--