Hiya, welcome to cubase joy,
one way you can do this is by selecting the play tool (hit 9) and click on the bit you want to solo, only issue is that this will bypass any FX.
Another way is to create a group channel for all the vocals, solo the group to get the group, solo the channel to get the channel.
Another option is to create folder track for the tracks you want to group (if you don’t want group channels in the mixer). This works the same way but in the arrange window.
Cheers,
PC