They must beat Real Sociedad for group leadership. Then they can be the leader of the group, but we have seen in Omonia matches that they can have problems scoring goals. Real Sociedad, they are one of the strongest teams in Spain and even a draw will give them an advantage against ManU. Manchester United should look at the Real Sociedad match as the final and definitely win that match. Otherwise, they can be matched with difficult teams from UCL.
If Manchester United can beat Real Sociedad away (which I doubt), then in this way they will only equal them on points, but the goal difference at the moment is Sociedad +7, and Manchester United +3. Let's be realistic about getting around Sociedad even if Manchester United wins, so most likely they will be second, since it is clear that the Sheriff will definitely not be able to compete with them in this.