All transmitters come with a firmware installed, no need code. They have some predefined choices to accommodate what you are flying, fixed wing, quad, helicopter etc. We call making those choices, programing, which is not to be confused with computer programing or coding.
There are several open source firmware's available that coders have created (OpenTx, Er9X etc.). Great if you have those skills. But us mere mortals don't code, we make the choices (program) that the coders allow us to make.