profcaju wants to enable a plugin for specific themes only, as it’s not necessary for the Air Theme, which already shows topic previews. Heliosurge suggests exploring the Customize > Component section for similar features, such as Topic Thumbnails and Topic List Previews, which can be combined with plugins like Sidecar. However, denvergeeks clarifies that it’s not possible to selectively enable a plugin per theme, but Theme Components can be selectively enabled per theme.
In Customize goto Component. look through the components listed there. There will be a component installed with Air Theme giving you the preview.
In the Air theme it looks like your looking for Topic Thumbnails.
This one is similar and has other features when combined with a plugin(be sure to verify plugin is still actively developed if you want to use Sidecar)..