I've been searching for this but have not been able to find something concrete.
Could someone please help whether it's possible to queue a build based on label in VSTS?
Link here - Label in TFS
Git
If you are using Git version control you can use the tag as shown below. Git tags are quite nicely supported in web interface and builds.
Selecting Tag when queuing build
Getting the source by tag for build
TFVC
TFVC is not supporting label in Code tab of web interface. But it is supported in Visual Studio.
Queuing a build for code in TFVC label should be prefixed by L.
For my label "TFVCSampleLabel" a build is queued like shown below
Build done for Label