You've kind of asked a dangerous question by being so vague and not mentioning how old they are or what you would actually feed next. Thge normal progression of feed is
From hatch until 4 to 8 weeks old - feed Starter
from when you stop Starter until you switch to Layer - feed Grower
When you get your first egg or they turn 20 weeks - Switch to layer.
It really does not matter if you switch from Starter to Grower at 4 weeks, 8 weeks, somewhere in between, or even a little later. Whenever you run out of Starter, switch to Grower.
Do not start Layer until they all are old enough. Layer contains extra calcium that can harm a growing chick.
There are a lot of other options. Instead of Starter then Grower you can sometimes buy a combined Starter/Grower and just feed that.
You can feed Flock Raiser fromthe time they are hatched until you switch to Layer.
You can feed Grower or Flock Raiser and never switch to Layer. Just offer Oyster Shell on the side so they can get the extra calcium they need from that.
This may sound complicated but it really isn't. About anything will work as long as you don't feed Layer to chiciks that are still growing. That's where the danger comes in.