What are the linguistic and rhetoric devices used in this piece of text?

[Relytsikcaj]

This is a headline from an advertisement for Barnado's

The headline reads.

"This is Emma. She's only Little"
"So you shouldn't have any trouble fitting her into your will"

There's clearly some play on words here, which has a term. What linguistic devices/rhetoric devices are used.

I can see some elements of colloquialism, and the use of personal pronoun "you."

But the "She's only Little" - "So you shouldn't have any trouble fitting her"

Is this a metaphor?

 

[Tarheel]

The word "pun" is what you might be looking for here.

Say:

What literary/rhetorical devices are used here?

Is there more? Has something been left out?

 

[Raymott]

This is 99.9% likely to be homework.