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 Small Caps S?
Anywhere text is accepted: Instagram bios, TikTok names, Discord, WhatsApp, gaming profiles and documents. The full Small Caps alphabet is linked above.
What is the Small Caps letter S?
It is the letter S rendered as the Unicode character ꜱ (code point U+A731), part of the Small Caps styled alphabet. It is a single character you can copy and paste anywhere.