Hello,
Basically, the URL is generated automatically, so depending on your needs, you could try to implement some workarounds.
There are already related forum posts open that you might want to check out.
https://www.wix.com/corvid/forum/community-discussion/standard-document-link-names-best-way-in-wix
The forum post below offers a workaround that could suit your needs:
https://www.wix.com/corvid/forum/feature-requests/can-i-customize-a-document-url