The Debian GUI Installer provides multiple automated partitioning options. I've had no issues with "use entire disk and set up encrypted LVM" so far. But toady I had to install Debian on a disk that is preoccupied by multiple operating systems. In the beginning of the disk there is a Windows installation, and in the end of the disk there is an Ubuntu installation. There is one continuous space in the middle of the disk.
When I chose the "use the largest continuous free space" option it correctly selected the entire space but there was no automated process to encrypt the volume. So I have an unencrypted Debian installation in the middle of my disk. Is it possible to encrypt only the entire Debian portion of the disk after an unencrypted installation in the same way as the guided "use entire disk and set up encrypted LVM"? I chose to put "All files in one partition". If there are no native methods, can third party software such as Veracrypt help? If there is no solution but to reinstall, how should I partition next time to achieve what I want?