Convert shorthand form to full form

Questions
1

Mathematica offers the use of shorthand notation.

Can I apply some kind of a tool that converts a shorthand notation to a “long” notation?

For example, turn this

(3 + #) &[x]

to

Function[3 + #][x]

It would help me to understand the experts’ answers in the community so to better understand the notation and the Mathematica syntax.
[1]: Use Shorthand Notations—Wolfram Documentation

2

Not exactly what you are looking for

Hold[(3 + #) &[x]] // FullForm
(* Hold[Function[Plus[3, Slot[1]]][x]] *)

Hold, or any other construct that prevents evaluation is required, otherwise

(3 + #) &[x] // FullForm
(* Plus[3, x] *)

(x + 1) // g // FullForm
(* g[Plus[1, x]] *)

f @@ g[x] // FullForm
(* f[x] *)

Hold[f @@ g[x]] // FullForm
(* Hold[Apply[f, g[x]]] *)