No, you can't get past this limit when using the Screen Time API. I don't know if it will be lifted in the future as I don't work at Apple. You can file an enhancement request to them about this.
In the meantime, you could maybe use a dedicated Safari content blocker to achieve what you want. For example, I know that 1Blocker makes extensive use of these content blockers and the app is pretty powerful: https://support.1blocker.com/en/articles/6436183-quick-access-to-content-blockers-in-safari.