Just sit for a week on any expired domains service and find clean expired domains, even if not very strong, but to which there are links from authoritative sites.
Buy these domains, restore the content on them from webarchiv and when the ranking and index return to this site, redirect 301 page where the authoritative site links to your site to the exact same page.
And on the home page of the restored site, write text about your site, and put a link to it (a relevant link that fits the meaning of this restored site).
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If your site is about sports betting, and you restored the site about real estate, and put a link like this:
I'm sitting in my house watching the analysis of #link#sportsbetting#/link#....
You're done, you're in the shit.
And if you write something like this:
Look at this house I bought last week. (brief overview of the house). By the way, I got the money for it from a Red Socks win bet last month. Used the app from this site: #link#sports betting#/link#....
You are in the chocolate, the maximum weight will pass the link and the main page, you immediately go to 20-50 positions up in the Google keyword ranking (temporarily true, then a little sag, but not to the end).
Therefore, think with your head, not other places when you do something.