Wordpress. When Parameter is changed...background on single page wordpress site changes

Question

Morning all

So I am fairly new to wordpress. I am a developer more so in react and front end based stack. I have been given the following task which I am wondering how to perform in wordpress.

Here is the example of the url

thisismysite.com This site contains a particular background (in this case lets say a car)

thisismysite.com/background=boat This site contains the background image of a boat

Essentially I would like this all to come from one main site not duplicate pages

So if the param e.g "thisismysite.com/background=boat" is selected. It inserts the image of the boat instead of the car from perhaps a separate bucket server?

As previously stated. I am not entirely sure the best practice for Wordpress.

If anyone could help that would be great!