You may not be able to fully expand your chest because the joints between the ribs are involved.

He expanded his chest and spread his feet like a colossus.

He expanded his chest and heard a creaking sound.

He forced himself to expand his chest and took deep breaths.

And being unable to expand his chest, he could not breathe.

But instead of running away, he expanded his chest and took long deep breaths.

He took a breath that expanded his chest.

He expanded his enormous chest and drank it in.

He expanded his narrow chest with a deep breath and exhaled noisily.

The whole how-to program about expanding your chest was practically his invention.