Hello,
I have recently made a tutorial (in Polish) on Full Disk Ecryption - along with the BOOT boot partition, during the installation of the Linux Mint operating system. The configuration was made according to the following list:
Linux Mint 19.3 Cinnamon + Full Disk Encryption + LVM + LUKS + UEFI boot mode.

The PC configuration was first tested using VirtualBox. Then a 'real' installation was carried out on the physical target equipment. Both the configuration in VirtualBox and on the target equipment has been done correctly.

Details and the tutorial itself in PDF file, available at:

https://docdro.id/5wdBWxR

Maybe it will be useful to someone.