Something I've noticed on MTG - our characters have various ethnicities, and some artists struggle with this, especially those who rely on a narrow, trademark style. It's beneficial to adapt your style for different skin tones, facial features, and body types.
Analyze and reframe you work using technical terms. Rather than think "pale skin on dark clothing," think of "light area vs. dark area". That way, you have more aspects to modulate: like lighting dark skin so it contrasts the bg or lightening the bg to contrast dark skin.
When working with just lines, come up with different shape language to express things like wider noses and lips, different eye shapes, skull shapes. it's a great way to keep your character designs from having "same-face syndrome."
Finally, relying on specific "cultural wear" to express ethnic background doesn't always work in a fantasy world where those cultures don't exist.
Learning to draw different people helps convey "no matter your real world background, you fit into this imaginary one."
Learning to draw different people helps convey "no matter your real world background, you fit into this imaginary one."