A lot for the best performance with fullframe cameras depends on what camera, what lens, what postprocessing is used and how capable is cameraman of handling manual settings and shooting with it.
Basically, if you want it to be bad, it will be, but if you want to compare with point-and-shoot photographer, you should provide him with at least average hardware.
Actually the biggest advantage of fullframe in bad light compared to phone is colors, retaining more details and better natural bokeh.
On other side, there are some advantages to phones, like getting good results if you don't know how to handle real camera.
There are also some features not available on full size cameras, like electronic auto ND (not on this phone), bug screen, IR mode(not on this phone), resolution mode, auto hdr, in hand tripod,...