Recommendations on getting a police clearance certificate.

I have a job in a different country coming and need a criminal background check. I am American and have been in Thailand for about a year on covid visa, tourist visa, and some visa exempts. My question is the optimal way to go about this? Should I go myself or is it better to go through an agency? I don't like in Bangkok but will be there for a day to hopefully deal with everything next week.

Really appreciate any advice of how I should go about this or, if you have done this before, what you wish you had known previously thanks!