Be there, for the square
Charcoal, 4 bytes

Ｓ‖Ｏ^


Try it online! Link is to verbose version of code. Explanation:

Ｓ       Input the string and implicitly print it
 ‖      Reflect...
  Ｏ     ... overlapping the first and last character...
   ^    ... in the ↙↘ directions (^ is shorthand for ↙↘).