My understanding of the EU system is that it's far more proportional in representation, and a simple 51% isn't enough to have 100% control. Parties still need to work together and compromise.
We've already seen with Brexit that 100% control is not needed in a parliamentary system to destroy a country's livelihood. But my point was that AfD doesn't need something like "presidential control" of the EU, it would just need to start working with other far-right parties in the EU such as Hungary and France's RN to sow chaos from within. Is that very far-fetched? You can't tell me that most of Europe doesn't hold its collective breath at every French election, crossing their fingers that Le Pen's party doesn't win this go around.
It's not hard to imagine what kind of damage they could do to the EU if they took power in Germany and started working with Hungary to block EU legislation, veto sanctions, defund programs, etc.