WCAG success criteria that may be most applicable to this topic are:
When we talk about contrast consider the implications to people who use Windows High Contrast Mode when creating your maps.
W3C/OGC Joint Workshop Series on Maps for the Web in 2020
This contains a final report with a section that discusses accessibility that pointed out none of the existing map frameworks at that time met WCAG 2.1 success criteria.
W3C accessible maps documentation compiled by the Research and Development Working Group.
Maps for HTML Community Group, which is hosted by the W3C, has accessibility in mind from the start as they work to establish a media type associated with a new map HTML element.
A Plan for Accessible Maps touches on a number of things that also apply to other media content:
Accessible Digital Map Experiences: a mountain climb or walk in the park? (written by a "cartographer turned inclusive-design advocate")
Interactive Map Accessibility Principles
Additional resources on creating accessible web maps, as well as some that are for specific map libraries.
Interactive map accessibility may vary depending on the format or technology used. When working with SVG image creation consider ways to make them accessible: