a) To use this feature, system navigation buttons should be enabled: go to “Settings”->“Button & gestures”->“System navigation”->“Buttons navigation”.
b) Then go to “Settings” -> “Accessibility” -> “Accessibility Menu” -> “Accessibility Menu shortcut”, touch the trigger to activate it->touch “Allow” -> “GOT IT” ->the accessibility button
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Note: Available settings and menus may vary depending on device model and software version.