The sellers of social media likes and follows often utilize botnets or click farms, where either automated bots or actual people using numerous devices and accounts generate the interactions, and social media companies combat this practice by employing algorithms and machine learning techniques to detect and remove fake accounts and engagements, continuously adapting their methods to counter the evolving tactics of these sellers in an ongoing battle to maintain the integrity of their platforms.
Some would use a method to let users of certain social media to like/follow others in return of getting it back [for free users] and for paid users they just buy them instantly.