Say you have to find out URL schemas of 3rd party iOS apps, many of them. First download these apps using the macOS iTunes. Right-click one of the downloaded apps and select Show in Finder.

iTunes Show .ipa in Finder

This will open the folder of .ipa files at ~/Music/iTunes/iTunes Media/Mobile Applications which you then copy to another folder of your choosing. In this folder you now run the following script:

# Usage: $0 <directory of .ipa files> <output file with (app-name URL-scheme) pairs>
for file in ./*; do
  dir="$(basename $file .ipa)";
  unzip -uqd "$dir" $file;
  app_name_path="$(find "$dir/Payload" -maxdepth 1 -name '*.app')"
  app_name="$(basename "$app_name_path")"
  plist=$(plutil -extract CFBundleURLTypes.0.CFBundleURLSchemes.0 xml1 -o - "$app_name_path/Info.plist")
  scheme=$(echo "$plist" | grep \<string\>)
  echo "$app_name $scheme" >> ../schemas