Hi @Rolf1. Thanks for being part of GoDaddy Community! To clarify, you wouldn't need to change to a cPanel account just because you're using a Mac. The operating system of your hosting server and your ability to use it are not dependent on the operating system of your computer. However, if you want to change to cPanel, you may do so.
Unfortunately, there isn't an automatic way to move from Plesk to cPanel. You would need to purchase and set up the new cPanel account, move your website content and domains to it, then close the Plesk plan. You shouldn't lose any content if you do it correctly though. You may find this article helpful if you decide to make the switch.