The rules with Managers being ejected from the game is that they cannot remain in the dugout so they have to go into the clubhouse after the point of their ejection. However they are allowed to watch the game from stadium seats but they have to be in civilian clothes and cannot be close to their team's dugout.
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Not in MLB. Unless the manager did something so bad that the Commissioner felt he needed to suspend the manager immediately, the manager would be allowed to participate in the second game.