A bunch of a11y settings are documented in the extensions API docs, but are not included in preference_api.cc's PrefMappingEntry. Attempting to get or set these settings triggers an error, crashing the extension renderer:

    chrome.accessibilityFeatures.caretHighlight.get({}, console.log.bind(console));

[99130:99130:0216/165409.559499:ERROR:bad_message.cc(22)] Terminating extension renderer for bad IPC message, reason 8
[99130:99130:0216/165409.559625:ERROR:bad_message.cc(22)] Terminating extension renderer for bad IPC message, reason 8
[99130:99130:0216/165409.559657:ERROR:extension_function.cc(150)] NOTREACHED() hit.
[99130:99130:0216/165409.559680:ERROR:extension_function.cc(477)] Bad extension message types.ChromeSetting.get

Seems like every property after "virtualKeyboard" fails.

Documentation: https://developer.chrome.com/extensions/accessibilityFeatures

chrome.accessibilityFeatures spec: https://cs.chromium.org/chromium/src/chrome/common/extensions/api/accessibility_features.json?type=cs&q=accessibility_features&l=1

preference_api.cc: https://cs.chromium.org/chromium/src/chrome/browser/extensions/api/preference/preference_api.cc?type=cs&q=chromesetting+accessibilityFeatures+largecursor&l=154