How do I find out the files modified within a time interval?

find . -newerct "2020-01-30 00:00:00" ! -newerct "2020-01-31 00:00:00"

08

unix.stackexchange.com/a/185932

-newerct deals with the «Change» value of the stat output:
06

If you want to deal with the «Modify» value, then use -newermt instead.

unix.stackexchange.com/a/2803