Você pode usar o abaixo para procurar os arquivos que você está procurando e depois passá-los para executar a ação que você quer, no seu caso é copiar.
$ find /path/to/files/ -type f -mtime +25d -exec cp {} /destination/path/ \;
-mtime n[smhdw] If no units are specified, this primary evaluates to true if the difference between the file last modification time and the time find was started, rounded up to the next full 24-hour period, is n 24-hour periods.
If units are specified, this primary evaluates to true if the difference between the file last modification time and the time find was started is exactly n units.
s second
m minute (60 seconds)
h hour (60 minutes)
d day (24 hours)
w week (7 days)