We've seen that Angels can be locked in Coin's, or that Spirits of intellect can live in objects. Also that wizards can swap bodies. So here is a question. Could a wizard looking for a form of immortality send their mind/soul into an object (coin) in which they can possess people? I guess kind of like a horocrux from the HP series.
Or a ring? *hint hint nudge nudge*
Body-swapping has been demonstrated - Capiorcorpus.
Sanctums have been demonstrated - Bob's skull, Harry's grave, Lindquist's house, Demonreach (sort of)
Combining those two seems doable. As for possessing others? That also seems doable via black magic, combining the basic mental invasions done by Molly in PG with some of Capiorcorpus's abilities.
But I see some potential roadblocks. As a "naked soul", Harry's magic didn't affect the real world. A soul inhabiting an object could be subject to the same restriction. Bob isn't, but Bob isn't human, either. Being unable to affect reality might prevent the soul from using black magic on a mortal mind. We did see Harry jump into both Lindquist and Molly in GS, but that was consensual (though not how Molly would have wanted it).
Also, in addition what their magic an affect, one's magical potency seems tied to their physical forms as well. Look at Luccio. Post swap, her magical power was scuttled. Her skills remained, but the raw power she could put into them was much reduced. Using an inanimate object as a body instead of a living organism would likely reduce available power as well.
So I'm guessing possible, but impractical except as a desperate measure.