I just bought gscale Narrow Gauge 4-6-0 Painted Unlettered - Black. It said it was DCC Ready and Sound Ready, but looks like I have
to get a sound decoder to actually get sound. What is the most recomended Plug and Play sound decoder that will work on this engine.

so the term "DCC ready" can and has meant several things over the years...

Do you have the socket in the tender, or a board with solder pads or screws?

Below is the version that can take a plug and play decoder

(note: there is a smaller dummy board that is plugged into the main board in this picture, you pull that small board out and plug in the decoder)