I have windows xp and want to play fortnite
is that possible?
No
Because Directx 11 is needed for this and that does not exist for XP.
Fortnite currently supports DirectX 9
https://www.pcgameshardware.de/Fortnite-Spiel-16272/News/Keine-Unterstuetzung-fuer-DirectX-9-Grafikkarten-ab-Season-10-1288819/
So that would be possible now
But that depends on the season and is not in the question.
Season 10 is not there yet, we're only 9
Okay sorry thought it's about the next level my mistake.
Regardless of whether it works technically: Leave it. Windows XP is no longer on the Internet.
(Unless you're in the mood for malicious software that nestles in secret without your intervention!)
Well, even if the DirectX 9 is still supported, Fortnite does not run on Windows XP, so it does not work!
Fortnite runs on Windows 7/8/10. Not on Windows XP!