Make bold text for places that have no bold button: Instagram captions, TikTok bios, LinkedIn posts, X. Tap a style to copy it.
Limits: Instagram bio 150 characters, X (Twitter) display name 50. Fancy letters can count as two characters in some apps, so leave room.
These aren’t real fonts. Each style swaps your letters for look-alike Unicode symbols (mostly from the math and letterlike blocks), which is why it pastes anywhere text goes. The catch: screen readers may read styled text oddly, letter by letter, or skip it, and search inside apps often won’t match it, so people may not find you by typing your name. Keep your name, @handle and key information in plain text, and use styles for decoration.
Sans-serif bold looks closest to the bold you'd see in an app and is the easiest to read, which makes it the usual choice for a heading in a caption or post. Serif bold looks more like a printed book. Both include bold numbers. There are also bold italic, bold script and bold gothic versions.
Use bold for a few words, not whole paragraphs. Each bold letter is a separate Unicode symbol, so a screen reader may read it oddly, and the words won't be found by search in most apps. On LinkedIn and X that means a bolded keyword won't match a search for that keyword.
Apps that support formatting have real bold, which is better. In Discord, WhatsApp and Slack, wrap text in asterisks instead (**bold** in Discord, *bold* in WhatsApp and Slack).