Format selected words inside Messages
Apple’s Messages formatting guide documents entering a message, selecting text and tapping Text Format above the keyboard. Choose bold, italic, underline or strikethrough, or a supported animated effect. Start with a short phrase so you can distinguish an emphasis choice from animation. These documented controls format the message; this workflow does not select a new font family from installed font files.
Check the recipient and keep the wording meaningful
Apple requires iMessage for its text-formatting and text-effect workflow and says older or other operating systems may display plain text. Keep the message understandable without the treatment. Compare a single emphasized word with the whole sentence before sending; decoration should not be the only way essential details such as a meeting time are communicated.
Change local reading size as a separate task
For easier reading, Apple’s per-app visual settings guide directs you to Settings > Accessibility > Per-App Settings, then Add App and the chosen app’s settings. Adjust the Messages reading view independently of outgoing emphasis. The homepage’s copyable Unicode styles substitute characters; they do not invoke Apple’s native formatting, install a new message font or guarantee the same rendering on another device.
Your questions, answered.
Will the recipient necessarily see the same animated text?
Check Apple’s iMessage and operating-system compatibility guidance. The words should still make sense if rendered as plain text.
Is changing my reading size the same as formatting a sent message?
No. Local visual settings and the message’s selected text formatting are separate controls.
Sources & background
Sources supporting this page’s explanations. Practical examples are our editorial suggestions.