Love those ITX builds.
What case are you planning on using?
Many will accommodate a compact discrete graphics card.
If you will use integrated graphics, plan on using the fastest dual channel ram.
Assign plenty of system ram as vram.
I might also suggest that you consider the 9th gen processors which will use the faster HD630 integrated graphics.
I3-8350K is similar in price to the i3-7350K.
I saw an article which showed an asrock discrete adapter overclock panel on a z170 motherboard, so I might assume that one would be present on newer motherboards.
A look at the motherboard manual bios options may show such a setting.
The options were not very great though.