In the past, I’ve always just created a png image and used a site to convert it to an ico file. Then I would upload that to my images folder (replacing the default image). I did this through FTP, but that was years ago. They’ve added new ways to do it now.
It looks like you can upload it through WordPress – Appearance > Site Identity > Site Icon
That should work and might be a much easier way to do it.
There’s some other ways to do it too. Here are some tutorials that showed up on Google –
https://www.wpstuffs.com/custom-favicon-genesis/
https://www.magnet4blogging.net/adding-custom-favicon-genesis-child-theme/
http://dreamwhisperdesigns.com/genesis-tutorials/change-default-genesis-favicon/
Let me know if that helps.