From my correspondence with a few school last month unless anything changed you can’t apply for a ED visa outside Thailand at the moment.
i was told I had to come in on a tourist visa and convert within Thailand to get a ED visa by all school I contacted in Phuket at the current time.
The prices being quoted were not cheap and involved a 5,000 extension fee every 3 months at immigration also.
Thankfully we have the STV option repeated that covers how long I need to stay so didn’t follow up the ED visa route any further.
but unless anything changed it a very expensive option at the moment.