No, the Lexar Professional CFexpress Type A Gold 256GB is not compatible with the Sony A7C II.
Sony A7C II has a single SD UHS-II card slot and no CFexpress slot of any type. Sony's own Help Guide states this camera supports only SD memory cards (UHS-II compatible) — CFexpress Type A uses a physically different connector and cannot be inserted into an SD slot.
What works instead
See all compatible memory card for the Lexar Professional CFexpress Type A Gold 256GB →“This camera supports only SD memory cards (UHS-II compatible). When using microSD memory cards with this camera, be sure to use the appropriate adaptor.”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)