Vegetarianism could be fine if it's only with crops grown locally with not a whole lot of transportation involved, but that's not likely to happen anytime soon. Not to mention individuals have very little impact on the actual problem.
Even if we grant that this is all we need to do (I don't believe it is), you can't honestly be suggesting that 8 billion people are going to wake up this year and decide to voluntarily sacrifice such a primal desire.
Without big acts of legislation, this will only become reality when lab grown meat becomes significantly cheaper and available. That could be decades away, which is too late.
https://www.nature.com/articles/d41586-019-02409-7