These are the seat covers I bought. They have a GM part# on each piece so it was easy to match up since there are no instructions. No special tools needed to install. Everything these days clips or zipppers in place. The hardest job to me is the front headrest cover install. The rear headrests were super easy.
https://www.ebay.com/itm/2019-2020-NEW-TAKEOFF-OEM-CHEVROLET-SILVERADO-CREW-CAB-LEATHER-SEAT-COVER-SET/223803853359?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649