You apply for jobs in Canada. If an employer can’t find a Canadian or PR to do the job, then the employer applies for a LMIA. It costs $1000 and takes months to process. If successful you apply for a closed work permit…takes months. Few employers will go through the LMIA process. Most jobs will state you must be authorized to work in Canada.
You can’t improve your score because you are not eligible if your IELTS are too low. A job with LMIA will not help because you are not eligible for Express Entry.