Android has long had language options for different dialects. For example, English (US), (UK), (India), and so on. You may not feel the difference at first if you change to English from a different region (though having aeroplane mode sounds quite posh), but the settings are there for a reason and affect other parts of the UI and experience in various ways. For example, switching from US to UK English will change "$" symbol on the default keyboard change to a "£" and will also affect voice recognition in Google Assistant.