In the competition between the first and second place of different teams, in principle, the teams do not meet each other. The opponent who wins the first team will be weaker, but it is not absolute. Of course there are exceptions. For example, the strong team in Group B made mistakes, and the weak team ranked second and first. In this case, the second team in Group A took advantage of the first team. Of course, this situation is relatively rare.
2. 16 knockout, playing away first, then playing at home, with more buffer space. A really strong team is also good at away games.
And in the next round, the first place in the group stage can be a guest before the host, and the initiative will be stronger. The Champions League, the first guest and the second host, can be a lot easier away. It's best that they can win, but it's good that they can't win. In case of losing, the purpose and tactics of returning to China can be more clear and firm. This is the advantage.
Generally speaking, the advantage is not great! Mainly depends on the strength and injuries of the team, so as to judge how far the team can go.