You can use InviZible Pro to request new bridges from the Tor database.
If Tor is running and connected to the Tor network, all requests are made through Tor. Thus, you can request new bridges in countries where the Tor website is blocked.
You can connect to the Tor network with default bridges and make a request for the new bridges. This is recommended because default Tor bridges can be blocked at any time.
Sometimes it makes sense to connect to the Tor network using the meek_lite bridge and request obfs4 bridges. It is usually better to use obfs4 bridges because the meek_lite bridge is slow.