Make me a square!

Carrot, 11 bytes

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# #
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The program is in caret-mode, where #s are replaced with the input.

Charcoal, 5 3 bytes

Ｂ³Ｓ

Try it online! Edit: Saved 40% thanks to @carusocomputing. Explanation:

Ｂ   Draw a box
³   3×3 (second dimension is implicit if omitted)
Ｓ   Using the input character

Python 2, 32 bytes

lambda s:s+s.join(s+'\n \n'+s)+s

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For s='a' : the middle s+'\n \n'+s generates a\n \na and s.join turns it in aa\na a\naa (bold as are the ones that .join adds), because .join accepts a string as an iterable, then it is surrounded with the two missing characters