If you already have the Roku Express 4k (3940) which comes with the Simple Remote with no TV or volume controls, you can upgrade to the Roku Voice Remote. https://www.roku.com/products/accessories/roku-voice-remote
You can also find the Voice Remote at Walmart, Best Buy, Target, etc for about $20.
The other option is to purchase a Universal Streaming Remote that is compatible with Roku devices. (these are IR based -- line of sight). Again, you can find these at Walmart, Best Buy, Target, etc for $10-20.
If you don't currently have the Express 4k (3940), perhaps consider purchasing the Express4k+ (3941) that comes with the Voice Remote if budget allows.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660x, Premiere+ 3921, Express 4k+ 3941