Hi there icloud185,
iCloud isn't used as a backup storage method, but rather, as a syncing service. That being said, you mentioned wanting to sync less with iCloud and have more data stored on your iPhone. The link above your post also has tips to Manage your iCloud Storage.
While it's usually recommended to increase your iCloud storage should you wish to continue syncing with iCloud, and therefore with all of your other devices(including your iPhone), you can manage what's enabled/disabled for syncing with iCloud by going to Settings > Your Name > iCloud > Apps Using iCloud.
To increase your iCloud storage, which can increase up to 2TB(2000GB), this link has more details about doing that: iCloud+ plans and pricing
Cheers!