Not sure if its against forum rules to point out any particular panels here, but there are some on the social media section of the marketplace that are great. There isn't one main provider for everything, lots of people make their own now and specialise in certain social media platforms.
Providers buy the accounts in bulk, and have their own systems and software to run actions. For someone new to this business its very unfeasible as it costs a lot of money for the accounts, the proxies and software to run the accounts. You also take a loss when you lose accounts to bans (through mass actions taken in a short space of time) The higher quality the accounts, the higher the price to buy them also which is why cheap services are bad quality a lot of the time.