In module struct's docstring, it says:
"...
The optional first format char indicates byte order, size and alignment:\n
  @: native order, size & alignment (default)\n
  =: native order, std. size & alignment\n
  <: little-endian, std. size & alignment\n
  >: big-endian, std. size & alignment\n
  !: same as >\n
..."
The wording sounds like either native or standard alignment is performed, regardless of the optional first format char.

In comparison, the table in https://docs.python.org/3.8/library/struct.html#byte-order-size-and-alignment states that in all modes other than the default, no alignment is performed. This is the actual behavior of the module.