The bootstrap 3 documentation lists this under helper classes:
Muted, Primary, Success, Info, Warning, Danger.
The bootstrap 4 documentation lists this under utilities -> color, and has more options:
primary, secondary, success, danger, warning, info, light, dark, muted, white.
To access them one uses the class text-[class-name]
So, if I want the primary text color for example I would do something like this:
<p class="text-primary">This text is the primary color.</p>
This is not a huge number of choices, but it’s some.