Is 16GB RAM enough for running Photoshop and Chrome at the same time on a Ryzen 5 3600?

Yes, 16GB is the minimum. Photoshop uses 4–8GB and Chrome uses 2–4GB, so 8GB causes swapping, stutters, and low-memory warnings. With 16GB, the Ryzen 5 3600 has headroom for smooth multitasking. For heavy Photoshop work or 20+ tabs, 32GB is better, but 16GB is the sweet spot for most people.