As an American with a Thai spouse, I have a Krungsi bank account, which I got in my 40s. It isn't difficult, a decent bank branch should be able to assist. That noted I use Wise to transfer money and now they have cards. It is also my understanding that Bank of America opened a branch in Bangkok, so that's another option. Check out Wise. It seems the best rates.
I once had to send back notarized signed documents to Jomtien despite noting next day delivery and paying through the nose for it. The package still took about a week through USPS. It took 6 weeks for clothes. I just wanted to warn you that it will take a 'minute' to get there, but perhaps DHL may be faster...