It depends how you want that image to behave.
If you want it static like picture in museum you need to use static mesh
For image that always faces player (camera) you need material billboard.
Bot thos COMPONENTS are in viewport tab. THere is list inside on the left, and “add component” on top of it.
Add component that you need, apply MATERIAL (not texture), to component.
Then place blueprint in level.
Hmm i see you tried it with sprite. SO just place either static mesh or material billboard.
Create material out of your pluto texture.
Then in blueprint drag whichever component you choosed, and create (toggle or set node) VISIBILITY.
Imo Set Visibility is safer, you kind of control if its set or not. When you enter trigger set visibility to true when exit to false.
When it all works, set that component visibility to fase in construction script, or begin play, or in it’s default values in editor.