This excellent resource by Anna Melano, the co-founder of Betterleap, goes into great detail on cold emails and how/why you should use cold emails to get the job you like. She even goes through several examples of successful cold emails.
How to Write Cold Emails for Jobs with Examples - Betterleap - Hire faster with expert recruiters
This blog from TechRepublic details how you can get jobs that aren't even listed on the company website/job boards yet.
How to write a persuasive "cold email" for the unlisted job you want
This short article from Michael Dinich shows you the steps you need to craft a cold email strategy that can lead you toward your dream job.
The cold email that got me the job
This comprehensive course by Evan Kimbrell and **Zach Valenti expl**ores the nuances of cold email and how to build a cold email campaign and outreach from scratch. It also helps you improve your copywriting and networking skills.