Report from an end user using ChromeOS 63:

"I think all the accessibility customization should be under settings if possible since it seems to me that accessibility settings are in two places-- under settings and then separately under accessibility. Please let me know if I'm in error."

This is in the context of the user looking for key echo in Settings and I can repro that it is not in settings. 

This is borderline a feature request, but I'm opening it as a bug since I'd consider the current options to be workarounds if a user is looking to make changes in settings: keyboard shortcuts and the search + period menu.