If you still have the packaging, the full model and serial number are printed on a label on the outside of the box. The user manual also contains a "Specifications" section that lists the Model Number (though usually not the unique Serial Number of your specific unit).
An RCA TV serial number lookup is most useful for warranty and parts matching — but it’s not as simple as a smartphone IMEI check. Use the methods above, and when in doubt, contact RCA support directly with both your serial and model numbers. rca tv serial number lookup