How it works
Your letters are swapped for Unicode's Fraktur alphabet, the blackletter printers used across Europe for centuries: ๐๐ฆ๐ท๐๐ฏ๐ก. Tick Bold for heavier, easier to read strokes, ๐๐๐๐๐๐. Gothic C, H, I, R and Z come from an older Unicode set, so they can look a little different from the rest in some fonts. Digits stay plain unless Bold is ticked.
Capitals take some reading
Blackletter capitals look little like modern ones: ๐โญ๐โโ is ACSIH, and โ is often read as J. A word or a short name in capitals and small letters is easy to read; a whole sentence in capitals is not.
Questions
Is this really Old English?
No. Old English is the language of Beowulf, a thousand years older than this lettering; the name stuck to the letters. This changes how your letters look, not the words.
Can I make it italic?
No. Unicode has bold blackletter but no italic, so that box turns off. Screen readers read these letters as maths symbols or skip them, and search does not find them, so keep your real name, hashtags and links in plain letters.