Nope, the document template dynamic label doesn't allow you to do such.
What my approach is for many document templates is that I create a Non persistent entity, with attributes which captures all values I need for the doc template. In the microflow before generating the document, I create an object and fill all attributes with the required data. The document template contains a data view with non persistent entity as data source.
In you case you could add a string attribute, where you concat static and dynamic values and use that as dynamic label value.