Alternate uses for attacks

[NontheistCleric]

For example, a Pact of the Chain Warlock can give up an attack when using the Attack action to let their familiar attack. Are there any other abilities that specifically use Attack action attacks to fuel something else?

[PhantomSoul]

Grappling and other "special attack" options like shoving fit... not sure there are many alternatives to that suggested though!

Mercer's gunslinger has reloading replacing an attack as I recall

[KorvinStarmast]

For example, a Pact of the Chain Warlock can give up an attack when using the Attack action to let their familiar attack. Are there any other abilities that specifically use Attack action attacks to fuel something else?

Dash or Dodge uses your Action instead of an attack, as does Disengage.

[PhantomSoul]

Perhaps a bit taboo to mention its existence, but a weird case: as a beastmaster ranger, you can make an attack when you command your beast to attack (once you've got extra attack). (In this case, as written, you get an attack and your companion gets an attack, but only your companion took the attack action. DM might count you as having taken the attack action, but RAW doesn't have you do so.)