If I understand it correctly, you want to restore the volumes to smaller volumes (for example, going from a HDD to SDD). That is possible since VEB 1.1 if I am not mistaken.
In this documentation: https://helpcenter.veeam.com/docs/agent ... tml?ver=20
(please note this is beta documentation so there might be mistakes (and we are also happy to hear them
) you will see that you can do a manual restore
The next two steps then will guide you in resizing and changing the disk layout
Let us know if it helps