Almost certainly. TVs of that era set all the inputs in non-volatile memory in the factory. If it wasn't designed to have an RGB input, that input will not be enabled in the settings. Those settings are non user-definable, they are set over an i2C bus with a ROM chip.
It could be possible to dump the existing ROM and reverse engineer the settings by decompiling the ROM and using the jungle IC's datasheet (assuming it's complete enough), but that would be an epic amount of work and it is both beyond the scope of this thread and outside of the wheelhouse of most of us here. You would need someone with a decent level of computer engineering skills and extensive experience with relatively outdated i2C programming
Of course, that's also assuming that there is even some unused RGB input on the jungle IC in the first place.