iPhone 11 was sold with either 64 GB, 128 GB, or 256 GB of storage.
Which capacity do you have?
What is its current version iOS? Find the software version on your iPhone - Apple Support
How to check the storage on your iPhone and iPad - Apple Support
Manage your photo and video storage - Apple Support
How storage capacity is measured on Apple devices - Apple Support
Also review:
Clear the "Other" in your iPhone's storage - Use backup - Apple Community
Freeing up space on my iPhone - Apple Community
Your photos may not be the biggest clutter. Also review what is stored on videos and what is stored on (big) apps and/or rarely used apps. Game apps especially tend to be quite big, and their local files may constantly grow with use (e.g. explored area in open world games).
Aside from disk capacity on the device, iCloud storage is metered separately, and might also give “full” error messages. Please specify if “iCloud” is reported as being (almost) full on the current plan.