I had to print a file this week for a local artist, Laurie King, who drew his picture using an iPad Pro. He had exported the file sent it over for printing. The file had no embedded colour profile, so I opened it and used Adobe RGB as the working space, which is our default space, which we ask for files to be embedded with. I then soft-proofed for the paper we were printing on.
Although the print was a good match for our screen when Laurie collected his print, it wasn't quite what he was expecting. We opened the file in sRGB and it was a a near perfect match to the (uncalibrated) iPad screen and our next print was right on the money.
You can see from the results there is a huge difference and knowing and embedding the space you are working in is crucial, especially if your outsoursing your prints.
The print on the right (above) is clearly a far better match to the Lauries image (below).