A very relevant question. I use cold emails in my work, and I can say that the most important thing is to make the email personalized. This does not mean that you need to give discounts right away, but you can offer something valuable, for example, useful content. I also recommend using top cold email software for managing mailings. One such service is
https://snov.io/cold-email. It allows you to not only send emails, but also analyze their effectiveness. It is important that the emails do not look like spam, otherwise they simply will not be read.