Hi @MS Techie – It seems there is no such direct API to check group existence in Azure AD.
You can try to retrieve Security Group using
https://graph.microsoft.com/v1.0/groups?$filter=securityEnabled eq true
And then check for each group display name with your group name weather it exists or not in Azure AD as below
if(group.DisplayName.equals("ABCD_Group"))
Hope this will help you to get what you are looking for.