It's possible to specify which simulator is launched and used for net6.0-ios by specifying the _DeviceName MSBuild property:

$ dotnet build -t:Run -f net6.0-ios -p:_DeviceName=:v2:udid=<UDID>

You can get a list of possible UDID values by executing the simctl list command:

ie: /Applications/Xcode.app/Contents/Developer/usr/bin/simctl list

If you do not specify a UDID, you'll end up with the default iOS simulator which is mostly likely an iPad or iPod. 🤷‍♀️