It's been a while since I created a risen so I created one as a test. I wanted to see if I could create one that looked human but short and or young. Nope, not an option.

We can change the race, gender, skin tone, hair color, and profession.

We can't change it's height or age.

I used fire sprite parts to create this. They are listed as being little so you would think that the risen would be short and/or young looking but it's not. Height is listed in the description of the risen:
Your creation is average sized and male

I would like to be able to adjust the height or be based on the size of the specimens used to create it - i.e. little/small parts create a short person, medium/large create and average height person, very large/huge create a tall person. All of those based on relative size for the race.

Age adjustments would be similar to apparent player ages (those available through shifting and/or character generator.