I am also having the same problem updating Xcode, first with 11.1 and now with 11.2. Starting with the 11.1 update, it would get to 80%, start over, and then back at the 80% point it would say, “Unable to Download App. Xcode could not be installed. Please try again later.”
I tried several times, even restarting my iMac Pro, more than once. On Oct 28, I called Apple Support. The agent at first tried uninstalling Xcode and attempting a fresh installation. After that did not work, he asked me to download and run Malwareybytes. It showed my Mac was clean.
Finally he asked me to do a PRAM reset: https://www.makeuseof.com/tag/reset-macs-smc-pram/
This time, the "fresh" installation succeeded and I now had the 11.1 version.
However, today, Nov 1, when I saw that 11.2 was available, I started the update, but again had the same problem. It would get to 80%, restart, get back to 80% and again say, “Unable to Download App. Xcode could not be installed. Please try again later.” This time, I just tried the PRAM reset. It did not help. Doing an uninstall and a PRAM reset each time there is an Xcode update is something that needs to be fixed, as this problem is occuring with too many users/developers.