I just tested it and it still seems to work. You might have to choose "More" at the end of the default list to bring up the rest of the things that can open the KML. This is on 13.1.2. 13.2 might be different. iOS 13 is hands down the worst iOS update we have had to do in 5 years.
Please let us know if you are unable to do it and what version of iOS you are using.