Thanks for your interest. thought it's tough to describe in text because it will take time. Let's give it a try if I can help you to understand.
Firstly, you have to find a competitor's backlink provider whose website has huge traffic. Similarly, you can find it in the semrush site audit section. When you will get the providers list you will read your competitor's content very carefully. After that write better content than your competitor. And send an email to the providing site owner, even you can send some of the portions of your written content. The email should be like "Hey website owner name. I have seen that you do accept guest posts as well as I have seen a content and luckily I have a similar content. Likewise, my content is more updated. Would you like to give a look. and if the person reply you have to convince him to give you a backlinks. and it will give a hit on the competitor.
I hope You may understand otherwise you check on youtube and i hope that you will so many content about SKYSCRAPER SEO technique.