Constant 144 fps on a 144hz monitor with a good pc and graphics card?

I would like to play fortnite on 144hz, i also have a 144hz monitor and my graphics card is the nvidia geforz rtx 2070 super

but I often have fps drops (60-100 approx.)

do you have tips how I can keep them constant

By reducing the graphics quality or checking whether another component such as your CPU is limiting the game