Yes. You print size, color and other variant properties on the product label with a custom label template. To do this, you add a product field in the label editor and select Variant properties.
Adding size and color to the label
In the Shopware Admin, go to Settings → Content → Label templates and open a template or create a new one via Create label template.
Click Add elements and select Product field.
Select Variant properties as the product field and drag the element to the desired position.
Save the template.
If you want the name of the variant to appear on the label as well, select Product name with variant properties instead. You print properties that do not form a variant via Product properties. There you define whether all or only selected properties are printed and whether the name of the property appears before the value.
You can also add the Manufacturer to the label as a product field. Custom fields, however, cannot be added to the label.
You can find all elements and product fields of the label editor in How do I design custom templates for product labels?.