Hello,
Yes, the limit for DNS records per managed zone is 10000 by default [1], if you'd like to proceed with a request for increasing this limit, please feel free to reach out to your Google sales representative or directly with Cloud Support team [2] and they will assist you with this process.
Also you can always double check your limit by running the gcloud command in your console to verify if the new limit has been applied:
gcloud dns project-info describe [project_id]
You'll get a similar info as: "rrsetsPerManagedZone: 10000"
Hope this information helps.