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!

Can anyone suggest where to go for the police criminal check certificate?