All the apostles (other than Peter since he already had it) were granted like power and authority in Mt 18:18, but the chief power was given to Peter by virtue of Christ singularly laying the keys upon his shoulder earlier in Mt 16:19. The apostles can do collectively what Peter does individually. If the apostles corporately recieved it in Mt 16:19, there would be no reason to repeat Mt 18:18.
Christ purposely used the language of Isa 22:22 where the keys are passed down in dynastic succession from one steward of the kings house to the next steward. There was no corporate language used by Jesus.
Isa 22:22 • ‘And I will lay the key of the house of David upon his shoulder: and he shall open, and none shall shut: and he shall shut, and none shall open.’
Mt 16:19 • ‘And I will give to thee the keys of the kingdom of heaven. And whatsoever thou shalt bind upon earth, it shall be bound also in heaven: and whatsoever thou shalt loose on earth, it shall be loosed also in heaven.’
There is only one steward to govern the kings house, lest it be divided. Jesus gave Simon alone the keys and renamed him Cephas which is a transliteration of the Aramaic word for rock. When God assigns you a new name, you are given a new important vocation, just as when God renamed Abram to Abraham or when God renamed Jacob to Israel. That new vocation was head of the universal church. Its no coincidence that Cephas shares the same root as in ‘kephale’ which means head (Eph 5:23). In fact Jesus gave Simon a name only He possessed, because Peter is the Vicar of Christ (1 Cor 10:4).
In chapter 16, Peter was given authority before all the other apostles. If it was before the other apostles, then it was over them as well, because that jurisdiction was over the existing faithful. Moreover, Christ himself told Peter to feed his sheep, granting him universal jurisdiction (Jn. 21:15-17). Only Peter was told to stengthen the other apostles because he was the head (Lk 22:32). Only Peter was the beneficiary of Christ’s prayers that his faith would not fail, because Peter was steward of the house of God, and Christ can’t promise the gates of hell to not prevail if the head of His church falters. Only Peter received Divine knowledge by special revelation from God the Father because he was called out amongst the apostles as their leader. In fact, Peter is always listed first in the scriptures because he is the head, but for two obvious exceptions to the rule.