I just updated my iOS to 14.2. I don't know if it was always there or just arrived with this update, but after my email address in iOS Mail there is a blue disclosure arrow/semi-triangle. Clicking on it expands or collapses all folders for that email address.
On a Mac since 1984.
Currently: 24" M1 iMac, M2 Pro Mac mini with 27" BenQ monitor, M2 Macbook Air, MacOS 14.x; iPhones, iPods (yes, still) and iPads.
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