Use 'with knobs on' when describing something that's a more intense version of another thing.

Exaggeration Cue

It's informal, so use it in casual conversations, not in formal writings or speeches.

Casual Tone

It's a British idiom; other English speakers may not be familiar with it.

'With knobs on' can highlight an incredible amount of effort or quality put into something.

It's used to emphasize personal endeavor or the extent of a characteristic in oneself or others.

The phrase adds a colorful and creative way of emphasizing extremeness.