iPhone can’t restore because there is not enough space on iPhone

Hello ,

recently I’ve had my iPhone 11pro 256gb

swapped by Apple , as I damaged my last one .

I backed it up before we exchanged our devices so I would be able to continue to restore the back up on my new device .

in settings it says its 256gb so I can’t see why I’m finding this so hard.

firstly I had to update to the new iOS ,

then when I tried to restore it failed because there’s not enough free space on the iPhone .

ive also tried erasing all contents of the phone and restoring from the backup but I’m getting the same issue .

can anyone please help ?

thanks

Glenn