No, the Lexar CFexpress Type B Professional Gold 128GB is not compatible with the Panasonic Lumix S5 IIX.
Panasonic Lumix S5 IIX has two SD-only card slots (no CFexpress support). Its own spec sheet lists 'Card slot Slot 1, Slot 2 SD Memory Card / SDHC Memory Card* / SDXC Memory Card*' — CFexpress Type B uses a physically different connector and cannot be inserted into an SD slot.
What works instead
See all compatible memory card for the Lexar CFexpress Type B Professional Gold 128GB →“Card slot Slot 1, Slot 2 SD Memory Card / SDHC Memory Card* / SDXC Memory Card*”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)