Portrait Editor
Portrait Editor available in Debug Mode on pressing ~ (tilde) and clicking Portrait Editor is a great tool to test and check in-game models.
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From Ethnicity you can select a wanted ethnicity and hit Randomize DNA. It also resets colors used for clothes, headgears, etc.
From Gene you can alter the genes of the character. Need to say that hairstyles, clothes, headgear, etc. are also genes and can be found there too.
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After that, you have to select Sub group, a collection of possible variations.
With selected headgears or any other accessory gene, you can edit Strenght to scroll through possible variations.
To see your changes in-game right after editing, hit Reload Textures or Reload Assets buttons on the right. Reload Assets reloads .asset files. .mesh files reload on clicking 3D View.