find commands for BSD unix (or macOS) by file time.

find files modified within the last day

find ./ -Btime -1d

find files accessed within the last day

find ./ -atime -1d

find files created within the last day

find ./ -ctime -1d

find files modified between 50 and 100 days ago

find ./ -Btime +50d -Btime -100d