It looks like an uniform of a prussian Chamberlain (Kammerherr). Below you can see h.M. Emperor Wilhelm II. with his Chamberlains.
But I don‘t know if its an older Version or a Gala-Uniform?! Sometimes the Gala-Uniforms had historic pants of the 18th century.
(Source: Nach Rang und Stand - Deutsche Ziviluniformen im 19. Jahrhundert / Page 138)
I found it
It‘s a Gala-Uniform of a Chamberlain around 1910. On Picture „Abb. 5“ of the linked website you can see the Uniform on a royal Gala in Potsdam from Wilhelm II. with the historical pants. https://recs.hypotheses.org/3534