Yes, the Lexar Professional 2000x 256GB SD is compatible with the Sony A7 IV.
Lexar Professional 2000x is Video Speed Class V90 (260 MB/s rated write). Sony A7 IV's SD slot requires Video Speed Class V90 or higher for its top XAVC S-I 4K (600Mbps) mode per Sony's own Help Guide -- this card meets that class requirement.
“XAVC S-I 4K 600Mbps CFexpress Type A memory card (VPG200 or higher) SDXC V90 or higher”
“Faster Video Capture With V90 Class For Professional Users”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)