You do not type it from a keyboard; you copy it. Press the copy button above and paste it into any app. That is the whole point of Unicode styled letters.
Where can I use the Regional Indicator X?
Anywhere text is accepted: Instagram bios, TikTok names, Discord, WhatsApp, gaming profiles and documents. The full Regional Indicator alphabet is linked above.
What is the Regional Indicator letter X?
It is the letter X rendered as the Unicode character 🇽 (code point U+1F1FD), part of the Regional Indicator styled alphabet. It is a single character you can copy and paste anywhere.