As I'm sure you're awarestated, your question is equivalent to the existence of sucha large exotic 4-ball (a smooth $D^4$ which cannot be smoothly embedded into $\mathbb{R}^4_{std}$).
The existence of a flip would give rise to an exotic $S^4$, by gluing the $D^4$ at infinity using the flip diffeomorphism. Removing a counterexample(small) standard ball from this $S^4$ gives a large exotic $D^4$, since it contains a smooth submanifold $K'$ which cannot embed in $\mathbb{R}^4_{std}$.
Conversely, if you had a large exotic $D^4$, then you could adjoin a collar neighborhood of $S^3\times \mathbb{R}$ to get an exotic $\mathbb{R}^4$ which has a standard end (diffeomorphic to $S^3\times \mathbb{R}$), and therefore admits a flip.
Although I'm not an expert, I'm certain that the existence of a large exotic 4-dimensionalball is open (otherwise, the 4D smooth Schoenflies conjecture would imply the 4D smooth Poincare conjecture (a 4-manifold homeomorphic but not diffeomorphic to $S^4$). So
I think it can be safely assumedrealize that these flips arethis does not known to existanswer the spirit of your question, which is whether there is a large exotic $\mathbb{R}^4$ which does not have a standard product end and which admits a flip.