Yes, Legion 5 Pro has two NVMe PCIe 3.0 2280 SSD slots, the second slot is empty and has a pre-installed heatsink with a thermal pad. (I installed Samsung 970 Evo 1TB
Inside Lenovo Legion 5 (15) - disassembly and upgrade options | LaptopMedia España
So I have been thinking about upgrading SSD on Lenovo Legion 5 15IMH05H 81Y600STCK... - Troubleshooting - Linus Tech Tips