What do you mean by "true fullscreen". It should support fullscreen already...
And what resolutions do you need? Smaller ones or bigger ones? I don't think bigger resolutions would run fast enough on any existing hardware.
perhaps 1440p? My 2080ti runs 1080p at around 100-120fps. Though the game seems to cap at 120
My monitor is 1440p. https://i.imgur.com/0eeVvTX.png
He probably means exclusive fullscreen, the fullscreen in the game is like borderless windowed.