Hi @asafm7!
You could pause the Autoplay with JavaScript like this:
https://smartslider.helpscoutdocs.com/article/1966-pause-or-continue-the-autoplay
But if this is all you want to test, then it is pointless to do so, as a static image will always outperform any slider. Sliders (not just Smart Slider 3) have significantly more complex HTML structures, thus use more HTML elements (even if you just add 1 image). Furthermore, sliders use more complex CSS and JavaScript, and in the case of a single image you won’t need anything like this (at most only CSS to change the appearance).
So if you want to add only 1 image, without any other content, then do not use sliders for that, use the Gutenberg or your page builder’s Image element. If you want to show other content too besides that one image, that is when using a slider could be ideal, but only with the block type:
https://smartslider.helpscoutdocs.com/article/1800-block-type
or if you want to show more images, then with the Simple type:
https://smartslider.helpscoutdocs.com/article/1780-simple-slider-type
To sum it up: Sliders should only be used when you are building a more complex design, or at the very least more vivid content. Using a slider for a single image would be a total overkill.