Hello!
Gonna assume you mean content hijacking with pure SEO means (no hacking).
The steps are pretty simple (not easy, but simple)
1. Find some nice fat targets for yourself
2. Check their backlinks in your tool of choice
3. Buy expired domain with a stronger (or close to) link profile (relevancy is important)
4. Copy the site over to the domain you bought
5. Build links towards your site
6. Negative backlink attacks towards the original site (there is debate how well this works or doesn't work)
That's it, really. There is some finesse to these steps and different ways to execute, but if you know your SEO you should figure those out pretty fast. Big affiliate companies will DMCA complain before you can say "copycat". If they find out who you are, they might also sue the living shit out of you. I know of an ongoing case like this where Black Hat SEO is getting slammed by legal team of a very large affiliate company. Apparently they managed to subpoena the platform where he bought the expired domain.
Stealing other people's content is not something that I endorse - it's really not cool. I consider people who do this to be thieves, not much better than people who brake into houses really. For some sites, webmasters have poured their money, heart and soul into the site, just for it to be stolen by some asshole. But that's my two cents.