Yes, certain Slayer monsters and areas have specific requirements to access them. For example, the popular monster called "Cave Kraken" requires level 87 Slayer and completion of the "Lunar Diplomacy" quest to be fought. Similarly, the Abyssal Sire boss requires level 85 Slayer and completion of the "Abyssal Sire" miniquest. As you progress in Slayer, you'll encounter various requirements to access new content.