I am DM put 95% of my miles are from Air France flights. AF doesn't give its own Platinum members automatic upgrades to PE since it is a completely different class of service.

What their elite members do get is free preferred seating in economy. Some economy seats on AF must be paid for (exit row, first row, first few rows aisle and window). The cost of the seats vary based on distance and how prefrerred the seat is.

Delta elite receive the same benefits on those seats as do AF elite, meaning free preferred seating but not seats in Premium Economy which has different meals, amenity kits and other differences in addition to seats.