I also want to find a job in immigration, but my English is not very good. Is it better to do copywriting or something in the immigration industry?

It's simple. Copywriting in any industry and any company is just a clerical job. The copywriting of immigration companies is just a little more English, and the salary of immigration companies is not much higher than that of ordinary clerks. If you want to make money, look for a consultant, that is, sales in the immigration industry. This is a commission, and the salary flexibility is high. The only bad thing is that there is pressure, and wages are raised by commission.