Depends on the agent you use. Some are just “hand holders” and will prepare all the paperwork and ensure you have everything correct but you need to have everything pretty much exactly as if you were doing it in person. You go to immigration with them
Other agents do everything for you. You don’t need to be with them. You do need to have a Thai bank account but they “sort out” the funds. They will help you get a Thai bank account if you don’t have one (but you will need to be with them for that).
Obviously charges differ depending on the service offered.
Contact
@THAI *****************************
for specifics on what they will charge.