Absolutely you can, and they will love the stuff! But make sure they also have grit available to help in digestion. Small particles like sand are fine at 5 weeks, but as they age they will require progressively larger pieces. I used parakeet grit from Wally World (WalMart) at 1.29/ box. Anything other than chick starter requires grit. They can also get it from the ground if you let them outside in a well protected area/enclosure for short periods of time.
Mine get it in the run as I like to throw the seeds down then spray it so some get burried. Now that they are with my adults in the run, they have to share, pellets are given freely in the morning and night just not in the run during the afternoon, too many treats out there to worry about the chicks who are now also 5 weeks eating the adult pellets, the adults are bantoms so at 5 week they are now the same size.
My chickens get the sprouted Black Oil Sunflower seed as well as a sprout mix that I grow for my canaries starting at about 3 days old. I of course also give them medicated chick starter. But they love the sprout mixed with the sunflower treat 2X a day. They seem to grow faster and much healthier this way!