This position is great for deep penetration if he’s on the smaller side.
She gets on all fours on the edge of the bed, he stands behind to penetrate.
Large penises often hit the cervix from this angle; a more modest size will make her feel ‘full’ but not sore.
This also works with her legs between his, and his thighs on the outside of hers.
Add a toy…
Why not explore anal pleasure with this position using remote controlled toys? You can choose who controls the vibrations. Either she uses a love egg while having anal sex or a butt plug while he penetrates her vaginally, for sensations both of you will enjoy.