I'm not an architect, nor do I play one on TV. I am a consultant engineer on transportation infrastructure projects (mostly rail at present).
You will definitely struggle to walk in to a position unless you have contacts here ????
Do you have significant relevant experience? If so, getting a job in your home country with one of the international consultancy companies (e.g. WSP https://www.wsp.com/en-th) which has branches here could be a way forwards.
What makes you want to come to Thailand in particular? Other SE Asian countries (Malaysia, Singapore etc.) may be more accessible. India could also be an option.
I was very lucky in that 30 odd years ago I was unemployed in the UK and a mate asked me if I fancied a short contract in Korea (where? thinks I). He quoted what was, to me at the time, an obscene amount of money so of course I said yes.
There followed 15 years or so trogging around Asia (and a few years in Europe) during which I acquired a Thai wife (in Rome, Italy for flips sake). Then in 2004 the work in Europe dried up so we decided to move to Thailand where our savings would last a bit longer than in the UK. My Asian network was still very much intact and I got a consulting job here within a month. I'm still with the same small consulting company. ????
It's not impossible, even in the "restricted" professions, but it's not easy either. You need a lot of luck and a marketable skill. Good luck in your quest!