It’s estimated that 1 in 4 apps downloaded are never used and just as with your phone, apps take up storage space. Freeing this up makes it easier for iOS to operate. Even within the apps you do still want to keep, it is possible to slim them down by getting rid of some of the larger files within them. Head to Settings- General- Storage and iCloud Usage. Next tap on Manage Storage and look for items that are taking up a lot of space like podcasts and delete them.