Go to Settings > Sound & vibration > Phone ringtone . If you downloaded a custom file, select "Choose from local files" or "Add" to browse your downloads folder.
Avoid random websites. Use these high-rated apps from the Play Store (Search within the app for the keywords): Go to Settings > Sound & vibration > Phone ringtone
(Note: Due to copyright restrictions, we can only provide a link to a royalty-free version or a source where you can download the tone. Please ensure you support the original artists by streaming their music on official platforms.) Go to Settings > Sound & vibration > Phone ringtone