'termguicolors' 'tgc' boolean (default off)
global
{not available when compiled without the
|+termguicolors| feature}
When on, uses |highlight-guifg| and |highlight-guibg| attributes in
the terminal (thus using 24-bit color).
Requires a ISO-8613-3 compatible terminal. If setting this option
does not work (produces a colorless UI) reading |xterm-true-color|
might help.
For Win32 console, Windows 10 version 1703 (Creators Update) or later
is required. Use this check to find out:
if has('vcon')
This requires Vim to be built with the |+vtp| feature.
Note that the "cterm" attributes are still used, not the "gui" ones.
NOTE: This option is reset when 'compatible' is set.