ERROR: cordova-res was not found on your PATH

There are many offline/local options available for resizing Cordova resources. Ionic even has one now: cordova-res. I started the project in an attempt to deprecate the legacy resources service as soon as possible. You can try it today:

npm i -g cordova-res
ionic cordova resources --cordova-res

Hope this will help, Cheers !

Install and save cordova-res to your project node_modules.

npm i cordova-res@latest --save

then execute,

ionic cordova resources ios --force