Linear sensitivity makes Minecraft use linear sensitivity like other games.

Sensitivity

If you want your sensitivity to be like it is in other games, go to a sensitivity converter website like https://gamingsmart.com/mouse-sensitivity-converter/. Then you will need to input the game you want converted (and your DPI and sens settings), then select ("Source"), or Fortnite, as Fortnite uses linear sensitivity.

Note:

If you do actually play Fortnite and that's the game's sensitivity you want to use, note that Fortnite has 2 options: linear and exponential. You are probably on linear by default; however, do check if you are using exponential, since this conversion won't be identical if you are.