Styled letters, not an installed font
This tool covers bold, italic, sans, monospace and full width. It does not generate cursive, small or tiny text, glitch text, or cursed text. Most styles replace Latin letters with different Unicode characters. Full width also changes ASCII digits, spaces and punctuation. Inspect the code points if a destination app displays something unexpected.
A worked example
Bold changes A into 𝐀. Those are different characters even when both look like the same letter in a screenshot.
Before you use the result
Some screen readers, search boxes and apps handle these symbols poorly. Letters outside the supported Latin range stay unchanged. Keep ordinary text for important names, links and instructions. If styled text exceeds an app limit, compare its visible characters, code units and bytes.