PCB traces have resistance, and they have impedance. That is, a trace can act as a resistor, an inductor, and a capacitor. They are all three at once.
Resistance is independent of the frequency of the signals. The inductance and the capacitance of the trace are also (largely) independent of the frequency.
Resistance depends on the length and the cross section area of the trace.
Inductance depends on the length of the trace an how it is routed (curlicues make higher impedances.)
Capacitance depends on the length and the surface area of the trace, as well as the area of adjacent conductors - a wide trace over a ground plane has more capacitance to ground than a narrow trace crossing a narrow ground trace at right angles.
For a given trace, resistance, inductance, and capacitance are pretty well fixed and don't greatly change with the frequency of the signal.
Impedance, however, is frequency dependent.
That is inherent in the definitions of impedance for inductors and capacitors:
Capacitor:
$$ Z_C = -\frac{j}{2 \pi fC}$$
Inductor:
$$ X_L = 2 \pi fL$$
The impedance of a trace is therefore dependent on the frequency of the signal traveling through it.
Any time you want to know the impedance of a trace, you must know the frequency of the signal.
Transmission lines (strip lines, microstrip lines, and all their other PCB relatives) play the inductance and the capacitance against one another to achieve an impedance that is mostly independent of the frequency of the signal. That's thevsame as the characteristic impedance of a coax cable, except you can design it to an impedance of your liking rather than what the cable manufacturer delivered.
If you look into the (simplified) equations used to design striplines, you will see that there are no frequencies involved.
This Analog Devices paper on striplines has a lot of examples.
There are no frequencies involved, just the dimensions and properties of the materials used.
The impedances designed into a PCB will be indepedent of the frequency to the extent that the material properties and the precision of the making allow it.
At extremely high frequencies, you do have to use different materials and probably different tooling. The principles remain the same, though.