Effect - Smooth zoom

Is there any way to zoom in on a part of a movie, but not in a way that the movie is played back normally and zoom in just so that the movie, for example, approximates to a certain value for 10 seconds and then stays approximated for a certain time.

No.

See item 1 in the roadmap

https://www.shotcut.org/roadmap/

Thanks, “keyframable filter parameters” refers specifically to a smooth zoom or generally several filters, because I do not really understand the “keyframable” parameter.

https://en.wikipedia.org/wiki/Key_frame