Does implementing CQRS require using two physically separate databases for reads and writes?

No. At its core, CQRS is only about separating the models and code paths used for writing versus reading — it doesn't strictly require two separate physical data stores. A simple version can run entirely on one shared database, with a distinct command-side class handling validation and writes, and a distinct query-side class handling read-optimized queries, both pointed at the same underlying tables. A stronger, more powerful version uses two genuinely separate stores, often paired with event sourcing, which unlocks fully independent scaling of reads and writes and allows a purpose-built, denormalized read model instead of one general-purpose table trying to serve every kind of query. Both are legitimate forms of CQRS — the difference is how far a team chooses to take the separation.