Germany has the 2nd largest military in Europe, just slight smaller than France.[1]
However comparing it to a superpower is nonsensical. The US has the 3rd largest military in the world, beaten only by India and China who have populations in the billions.
But just below the US is Russia with the 4h largest military in the world, and the largest (by a huge margin) on the European continent.
Now the era of colonialism was only possible due to vast technological differences between the two parties, and the good luck of the Europeans finding empires in turmoil (Songhai, Benin, Aztecs, China, etc.). It’s extremely difficult to subjugate much less rule a far off colony. The US couldn’t even manage it with Afghanistan so I doubt they’d have much luck with Germany.
On the other hand, it’s much easier to conquer your neighbor, push them back and simply put your own people in place. Russia did that for about 50 years and ruled half of Europe. I would wager Germans have more to fear from a revived Russia run by an KGB agent who grew up during the time of Empire, than a US who was most recently run by a television reality show host.
1. https://rlist.io/l/largest-militaries-in-europe