Use the glyphs property on the Map style. Use this URL for free fonts:

glyphs: "https://fonts.undpgeohub.org/fonts/{fontstack}/{range}.pbf",

The list of fonts to use are available here:

https://github.com/UNDP-Data/fonts/tree/main/docs/fonts

On the layer, specify the font you want to use. Example:

'text-font': [
    'Roboto Regular'
],