Do immigrants have to go through an intermediary?

You can apply for it yourself. Generally, it can be divided into two types: skilled immigrants or investment immigrants. You can go to the website of the Ministry of the Interior (or the Immigration Bureau) of the country where you want to immigrate to see the information you need.

Skilled immigrants generally have requirements, such as what kind of skills and how many years of work experience. Just prepare the money for investing in immigrants, and prepare as much as the standards set by others.