Question about buying sites for backlinking

Hello there reddit members :)

I'm currently going through a slow backlinking acquisition campaign for my site.

I noticed that another way to get backlinks is to buy new sites from "Auction sites", some of them in my same niche are very cheap and between 2-4 months old.

Is it safe for me to buy these sites to link to my main site? Should I watch out for anything when I'm buying these kinds of sites?

Any advice would be much appreciated.

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Thank you