My iPhone is telling me that the maximum of my phone is full

Try to free up iPhone device storage see this Apple articles below:

If you need more space for an update on your iPhone, iPad, or iPod touch

If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support

How to check the storage on your iPhone, iPad and iPod touch

How to check the storage on your iPhone, iPad and iPod touch – Apple Support (UK)

Clear Other storage on your iPhone or iPad

Clear Other storage on your iPhone or iPad - Apple Support

What's the difference between device storage and iCloud storage?

What's the difference between device storage and iCloud storage? - Apple Support

See if anything here helps. 

Disk space - How to check the storage on your iPhone, iPad, and iPod touch.    *

 Disk Space – Free Up    -

 Disk Space – Free Up (2).  -

 Disk Space – Free Up (3).  -

 Disk Space - Free Up (4)    -    

 Disk Space - Free Up (5)   -  

ASC YouTube for how to free up space on your iPhone, iPad, or iPod touch