The main amount of review work seems to be in ranges.tex and concepts.tex.

We say

In a header synopsis, declarations of class and function templates should have a linebreak+indent after the template<...> head. In a class template definition, there is no additional indent after the template<...> head, and the linebreak after the template head is optional.

in our guidelines, so we always indent declarations (including class template declarations), but we don't indent class template definitions.

Your first example is thus wrong:

  template<class T>
  struct is_correctly_formatted;

Ah yes, indeed. Bad example then, but I think we have analogous violations for class template definitions.

Editorial meeting observations:

• A template head introduces a scope, which justifies indenting the subsequent code.
• A requires-clause does not.
• We could not indent either requires-clause or return type.

Another alternative: indent requires-by four spaces:

template<typename T>
    requires(foo<T>)
  int main();

We should also check how function definitions would look.

Tangential note on braces: Either full braces or no braces, the latter only when both arms fit on a single line (not: statement).

Tangential note on late requires clauses of function definitions: Indent by two, like the function body:

constexpr auto foo() const
  requires(is_same<T, T>) {
  return T() + T();
}

Editorial meeting consensus:

• (See 29.5.7 (<=> for an example):) For function declarations, both the early requires-clause and the return type should be on the same indent level (one level). The line with the return type should be short enough that the return type does indeed appear on the next line after the requires, i.e. no overly long explicit(very long...).
• Don't have both an early and a trailing requires clause (check with LWG).
• It's OK to not have a line break at all for late requires clause if it's short enough to fit.
• Update the wiki re all of the above.