Extended Reality (XR) is poised to become a flagship application in 6G networks, requiring the joint support of enhanced mobile broadband (eMBB) and ultra-reliable low-latency communications (URLLC)—a service class beyond the capabilities of current 5G systems. To meet these demands, 3GPP Release 18 introduces a Protocol Data Unit (PDU) Set-based quality of service (QoS) framework, necessitating XR scheduling schemes that are both PDU Set-aware and capable of satisfying stringent QoS requirements. This paper presents a downlink scheduling framework tailored for XR services in 6G, incorporating a novel mechanism for tracking PDU Set delay. Employing this framework, we formulate XR scheduling as an optimization problem that enforces PDU Set-specific QoS constraints and solve it optimally to maximize the number of XR users meeting their service requirements. Simulation results demonstrate substantial performance improvements, achieving 20–30\% gains over state-of-the-art delay-reliable schedulers and multifold gains over traditional approaches.