Здесь javascript уменьшение пригодится, вы можете настроить его под свои нужды ..
const paragraph = "Know someone who can answer? Share a link to this question via email, Twitter, or Facebook"
let paragraphWithBreaks = paragraph.split(' ')
.reduce((accum, curr, idx) => {
if (idx && (idx+1)%3 === 1) {
return [...accum, "</br>", curr]
} else return [...accum, curr]
}, [])
.join(' ')