The Web Content Accessibility Guidelines require a minimum target size for interactive components in any context, which includes desktop computers, for WCAG 2.2 AA conformance. From a conformance standpoint there are some exceptions, but the exceptions are based on the content, not on the device.
Target size, meaning the clickable area to activate an interactive component using a pointer device, has a significant impact on how easily people can use interfaces. Adequate target sizes help all users avoid missing their intended component or worse, unintentionally activating a nearby component. Particularly for users with disabilities that affect their ability to accurately click a small target, a large enough clickable area is essential. Common examples include users who experience tremors, who have disabilities that affect fine motor control, or who use assistive technology that is not suited to precise targeting.
Additionally, even if you intend or expect users to only access your content via a desktop computer, the reality is likely much more varied. Numerous options for input modes and pointer devices are available to suit individual needs. Users who require, or simply prefer, touch screen monitors, tablets, or other input options must still be able to access your content.
To learn more about other accessibility considerations for user interface design, explore our Accessibility Concepts for Designers course from Accessible Web Academy.