Usually not with a default pihole setup. Most smart TVs hardcode a dns server of 8.8.8.8, or one the company runs (rarely), which gets around a default pihole setup.

See the recommendations on this thread for the additional work you'll have to do: https://discourse.pi-hole.net/t/recommended-strategy-for-cli...

Some consumer routers may not allow the configuration necessary at all.

Likely, assuming your router is intercepting and forwarding all port 53 traffic to it (since they tend to hard-code a DNS server). If they hard code an encrypted DNS client, a custom encryption solution or DOH or otherwise, it can’t be defeated via the network and you’re better off not supporting these practices financially by purchasing the product.

If you can block access to their hardcoded DNS servers, sometimes they'll fallback on what the network provides.