title says it all, possibly a command that tells you it or as redstone told me about the plugin that puts it in the tab menu.
I'm overall neutral on the matter. Players are able to check their ping using different Minecraft clients/external ping checking methods, so it isn't a feature that is needed. I'm sure many players would like to easily know their ping when playing to help figure out where their issues are coming in. I know many modern games, or at least ones that I play provide exact numbers for a player's ping, which many people have grown accustomed to. In-game ping reporting is generally a decent bit off on Minecraft, though, usually around 2 times higher than what your actual ping is. This can get slightly misleading, as a player who's true ping is around 40-50 could be reporting at upwards of 100 or higher from in-game reporting. Here's some screenshots from Mineverse, where they show the ping in the tab menu. I also showed my ping as reported by console commands to compare. My Mineverse ping was generally showing up between 50-80, while my console ping generally gave a range of 30-36.