Your LG G6 is equipped with a microSD (The single SIM version has a designated slot; The microSD card takes up the SIM 2 slot for the Dual SIM version) memory card reader. If your laptop or personal computer can also read that kind of card (Most laptop computers are so-equipped), you should be able to transfer music files
The LG G6 is an Android smartphone and the Android market offers a bunch of free ringtone apps such as MP3 Ringtone Maker, Myxer and more.
Learn more about making your own free ringtones
Here is a sample of the all free ringtones (compatible with your LG G6) we offer:
Free 'Unclassified' Ringtones Free Ghost Ringtones Free Short Ringtones Free Far West Ringtones Hear All Our Free Polyphonic Ringtones