You can find free klingelton download sites by searching through the different categories, as well as by genre. Many sites will allow you to preview a preview of a ringtone before downloading it. Some will prompt you to save the file. iPhones and Androids can skip this step. Some sites have a tutorial that walks you through the process.
iTunes does not support transferring ringtones from one device to another, but there are other options. One of them is iMyFone TunesMate, which supports iOS 14/13/12 and can transfer ringtones from your computer to your iPhone.