My software-manager doesn't have Veracrypt - which is no surprise, since Veracrypt is not in the debian repository and - as far as I know - also not in Solydxks repository. It's probably ok to use it anyway (I don't know) but I don't think it's installable via Softwaremanager.
Single files for transfer can easily be encrypted while archived - there are several encryption methods available, depending on your filemanager, and there is 7zip.
The debian default method would be ecryptfs but I couldn't find a gui. It should be possible to use a script for some filemanagers (f.e. Nautilus).
For Thunar there's a CustomAction described here: https://help.ubuntu.com/community/ThunarCustomActions
using bcrypt. It might be possible to adapt this using other methods but I haven't tried.