Let $\Omega=\{1,2,3,4,5,6,7,8,9\}$ and let $G\leq\mathrm{Sym}(\Omega)$ be the group generated by the following permutations:
- $(1, 2, 9)$
- $(4, 5)(7, 8)$
- $(1, 4, 7)(2, 5, 8)(3, 6, 9)$
- $(3, 6)(4, 7)(5, 8)$
This is an example with $n=9$, with $G/O_{2'}\cong S_4$. If you want $G/O_{2'}\cong A_4$, remove the last generator.
To get larger examples, we can simply use direct products: let $H$ be a group of odd order acting transitively on $\Omega'$, with $|\Omega'|=3^{m-2}$ (for example, an elementary abelian $3$-group acting regularly). We can view $G\times H$ as a permutation group on $\Omega\times\Omega'$ with coordinate wise action, and it has the required properties.