Which airline are you hoping to fly with, it won't be Thai, Qantas, Jetstar if you are talking about Australia.If you were to check airport activity at various airports it is obvious that Airports are operating at less than 10% capacity and that will not change in the near future. Some are saying there is no problem getting out, but that is only possible by the limited number of destinations which may not include where you want to go. There are rules that apply to both the departing and arriving country.
It is currently not possible to say when foreign people will be allowed into the Kingdom. There is much speculation, however the best suggestion is to pay attention to government sites and not newspapers and gossip. At the moment the government is still trying to return Thai citizens part of the problem is the number of quarantine places available. There is no confirmation how they will open the gates, it could be on a case by case basis especially those with work permits, it could depend on where you come from as they may have travel bubble between like minded countries even this will take time to happen. I am personally stuck in Australia hoping to get to Thailand however Australia is not allowing its citizens to leave the country before September for example.There is no point in making any visa application until travel is permitted. All that we can do is watch and wait.