Is there a way to display Unicode flags by installing a specific font? If so, which?

Regional Indicator Symbols were introduced in 2010 in Unicode version 6.0, based on the two-letter international code ISO 3166-1, and also added support for emoji and a limited number of national flags. These symbols were badly named from the beginning, since they only support national codes.

Up to today, they are very badly supported by Unicode glyph engines, but that has not stopped the Unicode consortium from evolving in version 10.0 from June 2017 the number of possible flags from 26x26 two-code-points national codes to multi-code-points regional flags.

Given that even today, seven years later, country codes are almost always simply displayed as two letters rather than as one, not daring to mention their display as flags, I wouldn't expect the new standard to be implemented any faster.

If you are looking for a font that already supports the latest standards, see the BabelStone Flags font, which can be downloaded at the end of the linked article:

BabelStone Flags is a font that supports multicolour flag glyphs for Unicode character sequences representing various national, sub-national, supra-national, and miscellaneous flags. The current version of the font includes glyphs for 130 flags in total. At present the only Windows applications I use that fully support this font are Microsoft Word 2016 and the Firefox browser, although most other browsers (such as Chrome, Edge, and Internet Explorer) do partially support the colour glyphs in this font.

This font supports the two mechanisms for representing country and region flags described in the proposed update to Unicode Technical Standard #51 (Unicode Emoji): Regional Indicator Sequences and Flag Emoji Tag Sequences.

References :

• Unicode’s encoding of national flags is just crazy enough to work
• Regional Flag Support For Unicode in 2017

Google have released their emoji font, which include flag characters for the "Regional Indicator Symbols", at https://www.google.com/get/noto/help/emoji/, which would work for Android and Linux.

The webpage description stated that, colored font (and thus colored emoji and colored flags) does not work on macOS and Windows, but there are some applications, including various browsers, in which these fonts would work.

You can use one of these fonts:

• Twitter Color Emoji
• Twemoji Mozilla
• EmojiOne Color