I see two ways for it.

Having the cert should indeed indicate experience in the area. Cert exams should be about validating what you already know not cramming your head full of test answers the pimp your resume. The exam requirnments alone can often provide basic validation of experience; wrote your CISSP.. unlikely you have less than five years experience in infosec.

Reading the cert textbooks on your own is great for self-directed learning or just refreshing/validating your current knowledge. If the cert covers a new area of interest.. the textbook can give you an overview along with all the tangents to follow for more information or specialization.