Encrypting Local

As far as I understand crypt remotes saves the transferred files encrypted (on local or remote).
Is there a way to create a remote of local directory as if it is encrypted?
So we can mount it and back it up with 3rd party tools encrypted.

No. You can’t do a reverse like you can in encfs.

Just mount the normal remote (.e.g. b2: with a bucket b2:crypt) instead of the crypt remote (e.g. b2_crypt: that points to b2:crypt) and then you have the encrypted files mounted locally. You can then access the encrypted files with any tool you like. You can also treat a local mount with crypt encrypted files like a remote, e.g.
type = crypt
remote = /media/.b2/crypt

This is useful if you mount the normal remote with something other than rclone like acd_cli or node-gdrive-fuse or plexdrive.
But it seems like you want the encrypted files, so no need for the local “remote”.

That would be great feature