Stretching syllables to make lines scan

Some bands take single syllables words and turn them into two syllables. A famous example: Rock n' Roll Star by Oasis. Liam sings "roll" to sound like "rowel". It's helpful because it keeps the line iambic - "A rock n' rowel star".

I've also heard Frank Carter sing "smile" as two syllables on the song Heartbreaker. It sounds like "smi-yul". I have a few questions. Is there a word for this technique? Are you aware of it too? How do you use it yourself? And can you tell me more examples? 😊