Go to https://piefed.social/user/settings and choose 'OpenDyslexia' in the Font setting, halfway down the form.
This font looks odd to me but I'm told that it really helps some people. If you're one of those people, please let me know if you have any preferences around letter spacing or line height, etc.
Edit: PieFed also has Atkinson Hyperledgible
Its worth knowing that to my understanding, research doesnt actually support the idea that its easier to read these fonts with dyslexia, so it may not be the most useful diagnostic
Which shouldn't preclude people from using it if they find it helpful, which is why I don't generally bring that up, but if you wish to determine if you have dyslexia probably better to rely on any other evidence or experiences you have with respect to reading difficulties