IPhone XS MAX 2020 Model issues

Hi there, I have an iPhone XS Max 64 gb and I’ve only used around 18gb of my storage, however it’s saying the system is taking up 43gb of the storage... how is that even possible? I literally just got this phone last year. My sister has an iPhone XR 2018 model and has used way more storage than I have and somehow her system is only taking up 5gbs of storage and her phones running on a newer update than mine.