There is no OOB feature to identify user availability in MSD.
You can use below custom code to identify user is logged in to CRM today or not.
var query = new QueryExpression("audit")
{
ColumnSet = new ColumnSet(true),
Criteria = new FilterExpression(LogicalOperator.And)
};
query.Criteria.AddCondition("createdon", ConditionOperator.GreaterEqual, DateTime.Today);
query.Criteria.AddCondition("callinguserid", ConditionOperator.Equal, guid);
EntityCollection results = Contextservice.RetrieveMultiple(query);
if (results.Entities.Count > 0)
return true;
return false;
