I'm not arguing that spread is most important aspect but it's something....
https://www.wcnc.com/article/sports/nfl/panthers/panthers-second-largest-upset-in-franchise-history-packers-win/275-8a802c46-9694-455a-8cee-4ddb5ff08fea
Largest Spreads of Wins in History:
1995 Week 10 – 13-7 over San Francisco (14-point underdogs)
2000 Week 10 – 27-24 over St. Louis Rams (13.5-point underdogs)
2025 Week 9 – 16-13 over Green Bay (13.5-point underdogs)
2022 Week 7 – 21-3 over Tampa Bay Buccaneers (13-point underdogs)
2021 Week 10 – 34-10 over Arizona Cardinals (10.5-point underdogs)