Can I apply for another tourist visa or extension in Thailand after entering on a VOA and extending it for 30 days?

there is no voa that can get a 30 day extension SO let's go with the premise you most likely came into the country on a visa exempt entry (which means you showed up here without any visa and were stamped in for 30 days for free)

On a 30 day visa exempt entry you can get ONE 30 day extension, then you're done. SO if you did that you went automatically on amnesty and are allowed to stay until the 26th of Sept.

IF you want to stay after that you need to get a letter from your consulate OR from a doctor/hospital stating you cannot travel after the 26th of Sept and you could apply for a 30 day "unable to travel" extension.

You mean arrived on visa exemption? In general, no.

But I believe at the moment you can get another extension with an embassy letter saying you can't return home.

Or, a medical extension with a letter from a doctor.