Footer is set up through two ways under the Theme, either through Widgets or through HTML Block as a whole.
So, you can check out the Theme Documentation guide in this regard: https://xtemos.com/docs-topic/set-up-footer/
If you have used Widgets style, then you can find the Widgets under the Dashboard > Appearance > Widgets > there you can find the Footer Columns to add Widgets into.
Further, you can check the following guide too related to Widgets & Sidebars:
Hope this helps !