virtualbox.org

I am running Windows 10 Home with a Windows XP guest to play Simcity 4. However, with the host running DirectX 12, should I install DirectX 7 on the guest or would there be some sort of conflict? And, if there is, how can I work around this? Does Windows XP support DirectX 12?

Host video card is an Integrated Intel GMA X4500 HD Graphics It's all I have right now.

I think XP only went up to DX9, maybe 10. I doubt you'll have conflicts installing DX7 in your guest, but your guest has a Virtualbox video card, and it may or may not work. You may need to install 3D support in the Guest Additions, which has to be done in XP's Safe Mode in the guest, perhaps before you install DX7. It has been reported that games don't work well in virtual machines, and if they need fancy graphics support maybe not at all.
Take good backups just in case...

I'm just asking if installing DirectX 7, 8, or 9 on the guest will conflict with my host machine running on DirectX 11 or 12. I just don't want to mess up my graphics card.

Wait, I reread your post and it makes sense now. The video card controlling the guest and the host are controlled by the same video card, but the guest has a different (Virtual or pretend) card controlled by the host card.
I tried to give the guest more video RAM and acceleration, but I already maxed it out:
128MB Video RAM
Monitor Count: 1
Scale Factor: 100%
{Checked} Enable 3D Acceleration
{Unchecked and greyed out} Enable 2D Acceleration