Ubuntu 20.04: Как я могу зашифровать другие жесткие диски в моей системе тем же ключом, что и мой основной диск?

You can encrypt your hard drives using Disks utility which is already installed in Ubuntu 20.04.

To be able to encrypt your hard disk you need to do the following:

1. If you have any data, make backup and delete the partition
2. Click on + Create partition in unallocated space
3. Next
4. Choose Internal disk for use with Linux Systems only (ext4) && Password protect volume (LUKS)
5. Next, write your password
6. Click on Additional partition options --> Edit Encryption Options
7. Disable User Session Defaults --> Enable Unlock at System Startup

I hope this will help you.