None. The Micro uses integrated graphics only. There is no slot for a separate card. 

https://www.dell.com/en-us/work/shop/optiplex-desktop-computers/optiplex-7060-micro/spd/optiplex-7060-micro

Manual is here- https://topics-cdn.dell.com/pdf/optiplex-7050-desktop_owners-manual_en-us.pdf

But sir the eGPU can connect graphics card with another Laptop by M.2 Port? dose it until cannot?

Thanks

Check the specs in the manual to see if it has the necessary connections. The Micro is a small desktop with limited features. It is not a laptop. 

EGPU requires a slot.

There isnt thunderbolt so thats not an option.

hi sir another EGPU come form China can use M.2 port to connect. Can we use it?

thanks sir

No idea.  Dell doesn't support Mini PCI-E EGPUs.

Some say eGPU V8.0 EXP GDC Beast

works.  Definitely not supported by Dell.

https://www.youtube.com/watch?v=2CU7fUZS9rQ

https://www.amazon.com/Laptop-External-PCI-Graphics-Card/dp/B00Q4VMLF6

https://www.amazon.com/Walmeck-Graphics-External-Independent-Version/dp/B07DQ93M43/