No, the ProGrade Digital CFexpress Type B Gold 128GB is not compatible with the Sony FX3.
The ProGrade Gold 1700 is a CFexpress Type B card. The FX3 accepts CFexpress Type A and SD cards only, and its Help Guide states CFexpress Type B cards cannot be used. The card physically does not fit the slot.
What works instead
See all compatible memory card for the ProGrade Digital CFexpress Type B Gold 128GB →“CFexpress Type B memory cards cannot be used.”
“CFexpress Type B 1700 Gold Memory Card | ProGrade Digital”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)