Storefront swatches are now keyboard-reachable, screen-reader labelled, and announce unavailable variants as sold out. Tab focuses a swatch, arrow keys move through values like a native radio group, and VoiceOver or NVDA read the option name as you enter the row and the swatch name on each value.
This works the same on product page swatches, collection card variant swatches, and product group swatches. No setting to enable.
Check out the Accessibility page for more details.