Use File → Export → Export As to batch-export multiple files in WebP format

Export As is single-document, yeah — there's no built-in multi-file batch for it. The usual workaround is an Action: record yourself doing one Export As to WebP, then run it across the whole folder with File > Automate > Batch. If you need per-file settings tweaked, a small JSX script driving the Export As machinery does it — the ScriptingListener plugin can capture the exact descriptor so you don't have to hand-write it.

Without a script , you need to create an action, then run the action via the batch command.

https://community.adobe.com/questions-712/export-many-files-at-once-in-webp-format-photoshop-1150574

WebP is not available as an export option. You would have to use a script or another application.

Please ask this in the Photoshop forum:

https://community.adobe.com/p/photoshop