Relation ship between Track width, Impedance, Dielectric and copper thickness
There is no simple formula, and no simple proportionality between the trace geometry and the characteristic impedance. There are approximate formulas, like these from Microwaves101



where



or, from Chemandy.com,



These are empirical formulas, developed by measuring designs with different parameters, and finding a formula to fit the observed data. There is some limited range of \$W/H\$ and \$\varepsilon_R\$ over which they are valid, which you should check before using the formulas. As you can see, they are also fairly complicated to calculate, not just a few steps on your pocket calculator.

These formulas were widely used in past times, when running an FEM analysis to estimate the impedance was a time-consuming task. Nowadays we can do that in a few seconds, and there's no real need to rely on these fitting formulas.