Depends on the implementation, you can make contracts do anything, and if the bulk of the currency is premined and in the hands of the corporation, they can manipulate its value freely. Not every cryptocurrency works the way Bitcoin or Etherium work, some are quite centralised (see XRP for example).

Meta could demand that ads on its platform are paid in metabucks, pay employees (partly) in metabucks and manipulate the market by controlling liquidity. Essentially they’d be their own sovereign corporation issuing its own currency.