I have not been sucessful yet, but here's the command. There's a wwdc session on Thursday, June 6th, 3:00pm PST. Hopefully the answers are coming in this session, but I'm going to a lab today. I have to get OpenSSL working.
$ xcodebuild -create-xcframework -help
OVERVIEW: Utility for packaging multiple build configurations of a given library or framework into a single xcframework.
USAGE:
xcodebuild -create-xcframework -framework <path> [-framework <path>...] -output <path>
xcodebuild -create-xcframework -library <path> [-headers <path>] [-library <path> [-headers <path>]...] -output <path>
OPTIONS:
-framework <path> Adds a framework from the given <path>.
-library <path> Adds a static or dynamic library from the given <path>.
-headers <path> Adds the headers from the given <path>. Only applicable with -library.
-output <path> The <path> to write the xcframework to.
-help Show this help content.Chriss-MacBook-Pro:~ cvbuskirk$