For a full list of HTML colors, with NAME and HEX code, please visit
https://htmlcolorcodes.com/color-names/

Useful Colors in Classic Editor

Burnt Orange #993300
Green #008000
Maroon #800000
Blue #0000ff (default for Links)
Royal Blue #3366ff
Red #ff0000
Dark Green #003300
Dark Azure #003366
Navy Blue #000080
Indigo #333399
Very Dark Gray #333333
White #FFFFFF
Black #000000

More Colors for Block Editor

Orange Red #FF4500
Dark Red #8B0000
Saddle Brown #8B4513
Rebecca Purple  #663399
Midnight Blue #191970
Steel Blue #4682B4
Dark Slate Blue  #483D8B
Dark Slate Gray #2F4F4F
Dark Green #006400