This is about the testfor command in minecraft
I am just wondering if I can add multiple coordinates to one part because this is an example on what I mean (note this is in command blocks) : testfor @p[x=x1,y=y1,z=z1 z2,r=r1]
No, you can't. Use two commands instead.
Also, consider if you really need /testfor, it's usually not needed and got removed in 1.13.