The grappling rules state, in part:
When you want to grab a creature or wrestle with it, you can use the Attack action to make a special melee attack, a grapple. If you're able to make multiple attacks with the Attack action, this attack replaces one of them. The target of your grapple must be no more than one size larger than you, and it must be within your reach.
[…]
Escaping a Grapple. A grappled creature can use its action to escape. To do so, it must succeed on a Strength (Athletics) or Dexterity (Acrobatics) check contested by your Strength (Athletics) check.
Does attempting to escape a grapple require a whole action (distinct from the Attack action)? Or does it just cost a single attack (as part of the Attack action)?
It says very clearly that a character can attempt to grapple a target using an Attack action, and if they have multiple attacks with the Attack action, this [grappling] attack replaces one of them. Shouldn't it be the case that escaping a grapple could also be one of those "multiple attacks?" I can't see the distinction with ruling it otherwise.
Best Answer
It says an action, so it requires an action. If it could be done as one of several attacks, it would say so, just like it says for making a grapple.
If you're the DM, you can houserule this, of course, but think carefully before doing so, because allowing one attack of Extra Attack to escape grapples vastly favours the players. There are some monsters that are only dangerous because of grappling, so making it easier to escape a grapple is fairly crippling for them. Also, due to the way Multiattack works, this will only make it easier for players to escape monster grapples, not for monsters to escape player grapples.