Your maximum charge speed is defined by your vehicle. If your vehicle maximum speed is 50kW, you will never charge faster than 50kW, even on a charger able to deliver 300kW.
If you are on a 300, 150 or 75kW charger, you will share the available power between you with the exception of the Chademo which will deliver a max of approx 50kW due to the cables current rating.
What can I do to improve my charge speed?
In general, the emptier the battery, the faster it charges.
Driving itself has a minimal effect on battery temperature, and you probably won't notice the difference in your charge speed.
Luckily, fast charging will heat up the battery more significantly, which will, in turn, improve the charge speed.
Additionally, some cars offer the option to pre-heat the battery. This has the most impact on your charge speed, especially in the winter. Some cars automatically enable pre-heating when selecting a fast charger as a destination in the car navigation. To learn more about this function, contact your vehicle manufacturer or search online.