No.
Gravity is compounding all lists you've configured via Pi-hole's Adlist UI.
Once you've added a blocklist there, Gravity will update its content once a week automatically.
Blacklists would allow you to add additional domains to your blocklists, either as an exact match or by a RegEx pattern. Those definitions would be static, of course.
If you want to expand your blocklists, go for quality and content, not for sheer volume.
Focus your attention on the sites you visit regularly - if they still show ads, go tune your blacklists until satisfied. After all, it’s of little use having a domain on your block list that you never visit.
If you are still seeing ads in places you visit regularly, How do I determine what domain an ad is coming from? has good insights on how to decide what sites to block.
As for Youtube, blocking embedded ads is almost impossible, as the bulk of them is getting served by the same domain as the content.
Depending on how you've configured your network to make use of Pi-hole, it may take a while for a client before it picks up Pi-hole as DNS server.
You may speed this up by disconnecting and reconnecting a client to your network, e.g. by switching its wifi on and off, or by power-cycling that client.