How to find proper codepoint for IconData?
The example below uses 0xe808 codepoint.
From where the codepoint data comes?
static const _kFontFam = 'TikTokIcons';
static const IconData chat_bubble = const IconData(0xe808, fontFamily: _kFontFam);
The Unicode code point at which this icon is stored in the icon font.
So you need font tools such as Windows Character Map or online tools like fontdrop.info to view font metadata;
static const IconData add = IconData(0xe145, fontFamily: 'MaterialIcons');