Coordinate systems are actually just simplified versions of reality. You don't max out your perception at 3 dimensions/4 with time: you can use physical properties such as color, texture, luminescence, transparency, etc. If you utilize these things to represent individual collections of values on certain dimensions you end up representing things approximating real physical objects, but a strict "dimension" must go from -infinity to infinity. There's technically infinite colors, but humans can only see ~1 million or whatever, let alone detect the difference between them with ease; it would require exceptional sensory appararatuses, but even still this can only approach infinity, as opposed to "the 4th dimension" which opens up a whole other "space" (I mean, literally) for you to play with. How do beings make this shift from approaching to actually accessing another dimension? Do they get more physical properties too? What's that like?