How does the car screens or screens like that being developed?

I am a beginner at coding . I have an idea but i don’t know how to develop “screen” . My project looks like a car screen (My idea is not about cars . It just looks like that) . Just basic screen like Nissan Qashqai screens . I don’t know where to start . I can make mobile phone apps . But I wonder how these things work . I dont think they are complicated as phones cuz they have just few functions . I want to design my own tablet with simple functions.

Sorry for bad English grammar . As I said I’m new .

It’s basically like your PC. There is a computer and as an output device, there is a screen.
This computer has an operating system (OS) which is mostly a vendor specific OS which is probably based on Linux. For the application itself, you can use various programming languages like Java for example.

If you try to build something like that, you can consider build an IoT device. There are plenty of modular devices like Raspberry Pi which offers add-ons like a screen or a connection device.