How will they do this, exactly?
Also, isn't the cost of real meat too low as it is? It hasn't priced in climate externalities that other people (including non-meat-eaters) have to pay for. Shouldn't meat include all of its costs, not just the ones paid by the farmers?
Easy. Heavily regulate the farmers with climate regulations including carbon taxes. Or pass emissions laws like they have in the Netherlands which would force ranchers to downsize their herds. This would drive up cost to produce and scarcity of the product.
As for the second part of your comment I truly am not sure what you're talking about? It seems like your sentiment confirms the first part of my answer.