Asked and answered by MLB.com:

Since the advent of the dual Wild Card playoff setup in 2012, it hasn’t been necessary for the league to utilize even the three- or four-team tiebreakers.

Mathematically, it’s unlikely to be an issue this year.

But as we enter the next to last week of the regular season, it is, at the least, a mathematical possibility in the National League.

Our 2019 tiebreakers piece covers various scenarios like two-way division ties and three- or four-way Wild Card ties that could still happen. But we’re reserving this space for the ultimate October appe-tie-zer – the five- or six-way-tie possibilities still on the table.

Consider this your Chaos Compendium, albeit with a necessary disclaimer that the tiebreakers that follow are our own creation and not actual MLB protocol”

https://www.mlb.com/phillies/news/crazy-2019-mlb-playoff-tiebreakers