It is fundamental that you specify the load across which the voltage is applied, and through which the current flows.
If the load is an Ohmic resistor, then current is linearly proportional to voltage.
If the load is non-linear (lamp, semiconductor diode, lots of other things), then the most you can say is that if the voltage increases, the current increases too.
If the load exhibits "negative resistance" (e.g. Tunnel diode), then an increase in applied voltage can produce a reduction in current (very special case).