WhatsApp does not have a built-in text highlighting feature
Use bold text by placing an asterisk on both sides of the word or phrase
Use italic text by placing an underscore on both sides of the word or phrase
Use strikethrough text by placing a tilde on both sides of the word or phrase
Use monospace text by placing three backticks on both sides of the word or phrase
For emphasis, copy the text into a notes app or editor that supports highlighting, then paste it into WhatsApp as an image or formatted text if needed