I'm trying to install a toilet in a shed/office detached from the house
I know where the main pipe is going down inside the house and there has been a basement bathroom connections made to it on the inside of the house (trying to finish the basement) unfortunately it wasn't made by me, and I'm not sure which way the pipe is going or if its even low enough because the shed is at least 30 feet away form that pipe

So what would be the best way to locate the pipe (im guessing the clean out would be the place to connect it) with out too much digging and if the pipe is not low enough what would be the best way to drain the toilet?

Hello, I would recommend contacting a plumbing co. that does line locating. They can also tell you the depth the sewerline is at any point in the system when they locate the line.
Then you can ask them to shoot the elevation from the finished floor of the proposed bathroom to the point where you will tie in your new sewerline to the existing sewer.
If you run a 4" drainline you can slope it at 1/8" per foot, at 30' you would drop about 4"or you could run up to 96' for every 12" of fall. Hope this helps you, goodluck ----Zeke---