View Source ExTDLib.Method.SetAccentColor (ExTDLib v0.0.4)

Changes accent color and background custom emoji for the current user; for Telegram Premium users only. Returns object_ptr<Ok>.

NameTypeDescription
accent_color_idnumberIdentifier of the accent color to use.
background_custom_emoji_idstringIdentifier of a custom emoji to be shown on the reply header background; 0 if none.

More details on telegram's documentation.