The iPhone 8 is a smartphone. Most smartphones should let you save any song found online by tapping and holding your finger on it and selecting 'save.' Once a music file is saved to your media library, touch-and-hold it and choose 'assign' from the drop-down menu.
Here are some of the free ringtones (compatible with your iPhone 8) we offer:
Free Horror Ringtones Free Ghost Ringtones Free Ringtones-a-gogo Free Techno Ringtones Hear All Our Free Polyphonic Ringtones