The demon slayers in the series "Demon Slayer: Kimetsu no Yaiba" adapt their fighting styles to combat different demons by studying their abilities, weaknesses, and behaviors. They often use a combination of their own training and knowledge passed down through their organization to develop strategies that are effective against specific demon types. This may involve using specialized equipment, techniques, or exploiting the demons' vulnerabilities to gain an advantage in battle. By understanding the unique traits of each demon they face, the demon slayers are able to adjust their tactics accordingly to increase their chances of success in combat.