Hi tullio0106,
I have created a quick code example that showcases you how to achieve the functionality you need.
In your html file:

    <smart-drop-down-list  drop-down-open-mode='dropDownButton' display-member="value" drop-down-height='800' drop-down-width='800'>
            <smart-list-item value="first image">
                <img src="path to your image" alt="">
            </smart-list-item>
            <smart-list-item value="second image">
                <img src="path to your image" alt="">
            </smart-list-item>
    </smart-drop-down-list>
 

And also some necessary CSS:

smart-drop-down-list{
	min-height: 35px;
	height: auto;
}
.smart-list-item-container img {
	width: 100%;
	height: 100%;
}
smart-list-item .smart-content,
smart-list-item .smart-overlay,
smart-list-item,
smart-drop-down-list {
	height: 300px;
}

Let me know if that works for you!
Please, do not hesitate to contact us if you have any additional questions.
Best regards,
Yavor Dashev
Smart UI Team
https://www.htmlelements.com/