I'll never recommend creating a custom component if there is a native one that does the job. But if you develop a custom tab bar, .tabBar accessibility trait comes to the rescue. Apply to a container view and its buttons will be announced as tabs.
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Images can automatically scale for accessibility content size categories, by setting the adjustsImageSizeForAccessibilityContentSizeCategory property to true, for any UIImageView you'd like to get its size adjusted. https://developer.apple.com/documentation/uikit/uiaccessibilitycontentsizecategoryimageadjusting/adjustsimagesizeforaccessibilitycontentsizecategory
You don't have to offer an alternative layout just for the accessibility category. You can actually compare content size categories. So you could tweak the UI already for anything equal to or larger than .extraExtraLarge, for example.
Check isReduceTransparencyEnabled to lower transparency. A great example is Spotlight. Not only transparency is removed but it keeps the main color of the background, it feels personalized and contextual but reduces noise and improves contrast.
