While Samsung's last couple of tablet-sized foldables already supports Samsung's S Pen, it doesn't have the space for the stylus on the foldable. But the next iteration of the Galaxy Z Fold might change that. There are reports that Samsung might finally integrate a slot into the Galaxy Z Fold5, which puts the latest nail in the coffin of the Galaxy Note line. It would also help define the Fold series as a productivity-oriented device.
The report from The Elec doesn't outright say there will be an S Pen slot but suggests it's being heavily considered by the company. Samsung reportedly cited the introduction of an S Pen holster as a key challenge it needs to overcome to make these foldable phones more attractive to consumers (alongside making the phone lighter and minimizing the crease).