That looks pretty bad. If it were me I’d slowly and with low heat use a hair dryer to warm the area. Once the leather has warmed up you may be able to massage that out. My guess is it won’t completely get rid of it but it can probably lessen it. After that I would use a good quality leather conditioner to moisturize the seat. Especially after using heat on it.
I regularly use Adam’s Polishes Leather Conditioner on my Laramie interior. The Sports/Laramies don’t have the real full leather like the Longhorn/Limited but the conditioner keeps everything nice and soft, looking new and it smells amazing.