Touch target sizes are recommended to be at least 44 x 44 points. Buttons in the navigation bar ( especially when not using nav bar button items), dismiss buttons, and custom toolbars, are use cases that tend to have smaller sizes.

You may also find interesting...
@NSSpain has a great history of having amazing accessibility talks in their schedule! “Accessibility in the Real World”, by @Sommer: https://vimeo.com/235317172 “How to build an app for everyone”, by @NovallSwift: https://vimeo.com/362163043 The super fun "Choose your own SwiftUI adventure - 3 Accessibility", by @twostraws and @PinkerStraws: https://vimeo.com/481768105 And, of course, this year's great "Bas: My Accessibility Story", by @basthomas: https://vimeo.com/751176747
@azzoor has this great video with some advice on how to set up your device for testing accessibility and a ton of tips will get you testing effectively in no time. https://m.youtube.com/watch?v=Ca1H6wF348g&feature=youtu.be

Anything representing a heading in the app should have the header trait. It allows for a faster way of exploring a screen and jumping to the part of the app you are interested in. Screens should also start with a header.