your local Immigration Office is where your TM30 is made.
Assuming you're a national from the 64 countries listed above, yes, it's a very easy process, 1 form to fill (TM7), add a picture and pay the fee, wait for your request to be processed and go away with your extension stamped in your passport.
Assuming you're American, you will get a 30 days exemption which you can extend 1 time for another 30 days at your local Immigration Office for 1,900 thb.
So you're eligible if you're unable to travel because of Covid-19 situation AND, as Stuart wrote, it's always at the discretion of the Immigration Officer.