Aluminum foil and plastic wrap can't absorb fluids. This means that the moisture from your sandwich will get trapped in the wrapping, resulting in a soggy sandwich.
Instead, use parchment paper to wrap your sandwiches. The porosity of parchment paper allows it to absorb the moisture from your sandwich, preventing soggy sandwiches.
When you tightly wrap your sandwich in parchment paper, it will squeeze all parts of your sandwich, which will make the ingredients in your sandwich adhere to each other securely.