In phoenix you have 1 channel, which can be grown or shrunk through a method called "splicing." When you have maxed out your inbound capacity, phoenix will make an onchain payment to grow the size of your channel.

A good practice here is to open a large channel (say, 500k-2m sats) and only need that on chain payment 1 time. If your channel is already open, expanding it (through splicing) to that range now while fees are relatively low is advisable.