You can either pass:

a withdrawal address and an amount of ETH validators (1 validator = 32ETH) to unstake and we will exit validators on your behalf. This only works with validators having a 0x01 withdrawal credential.
specific validators pubkeys, if you need more control. This works with any type of validator withdrawal credential, and is the only way to exit 0x02 validators

The endpoint will return a list of validators that will be exited together with estimates for exit and for principal withdrawal.

0x02 validators can only be exited by pubkey