The interactivity property specifies whether an element and its flat tree descendants (including text runs) are inert or not. Making an element inert affects whether it can be focused, edited, selected, and searchable by find-in-page. It also affects whether it is visible in the accessibility tree. The syntax is: interactivity: auto | inert
It is expected that for paginated carousel content, only content on the active page is focusable / included in the tab order. This is typically accomplished through the use of Javascript, as can be seen in the Web Accessibility Initiative Carousel example. This should be simple to express and accomplish in CSS using CSS Inertness.
Explainers: https://github.com/flackr/carousel/tree/main/inert