Fortnite has received a brand new recently on all the major platforms. The main addition for this update was the ability to run the game at 60 FPS and this also included the base consoles aside from the PS4 Pro and Xbox One X.
The update manages to enable 60 FPS support by adding dynamic resolution with it. This means the game now runs at a resolution below native 1080p on the PS4 and Xbox One with varying degree of result on both platforms. The analysis for the frame rate was done by VG Tech and they shared the following comment regarding the upper and lower limit for the dynamic resolution.
The Xbox One uses a dynamic resolution with the lowest pixel count found being approximately 1056×594 and the highest pixel count found being approximately 1520×810. The Xbox One appears to use temporal upsampling to increase the pixel count up to 1600×900.
The PS4 uses a dynamic resolution with the lowest pixel count found being approximately 1360×756 and the highest pixel count found being 1920×1080. The PS4 appears to use temporal upsampling to increase the pixel count up to 1920×1080 when rendering below that resolution.
The game might drop resolution but the result is a pretty much solid 60 FPS for the majority of the gameplay, which helps increasing the controller response and it is important for a online multiplayer shooter like Fortnite.
Fortnite is available now for the PS4, Xbox One and PC while you can get the Battle Royale mode for free on any platform.