Scene variants can be set in the Template’s scene selector by using the single chevron button < instead of the double << to select one or more variants.
The Scene Override behaviour control can be used to select the correct variant at render/tx time. This control is found above SCENE CONTROL OBJECTS, with all the available Behavioural Bindings, which override Scene Settings. Drag items from here onto the star icons on an individual Control.
If you bind the SceneOverride behaviour to a User Options control, it will automatically populate options; at template design time; with the available variants and present the user with a dropdown of choices. You may change the descriptions.
For automation, i.e. driving this from data, the SceneOverride behaviour can be bound to, for example, a Data Item control. Transforms could be used to convert a count value to a scene name: