S3/Openstack API Object Storage, Preauth & CORS

Hi all, I'm using S3 API on OVH and need to generate preauth requests for objects in bucket. That works fine.

I need to set CORS headers on the returned content. On AWS there's a mechanism to do this.

https://docs.ovh.com/gb/en/storage/object-storage/pcs/cors/

The above docs on the openstack swift API says CORS is not compatible with the S3 API.

If I set the CORS headers using swift CLI would they be sent for S3 preauthed requests?

If not does the swift API have an equivalent to preauth?

Apologies for any dumb questions or incorrect terminology, I'm new to this am very open to any advice!

Thanks,

Tony