How to sign out of appleid and keep photo images

I have to use a different appleid, but would like to keep my 17Gb and sync all images with this new account.

Apple support suggest to download everything to a mac and then transfer to another account :/ the problem with that is I'll lose "creation date" on all photos and they'll appear like been taken all at once (same day).

So I would like to keep my photos on my iPhone and sync with this new account.

When I go to sign out there's a warning saying that all data (including images) will be removed from this device (and kept in iCloud) which makes sense. But I would like to keep a copy of that and there's no option to do so. Only calendar, contacts, notes, etc..

I would like to hear from the community if there's a way to to that.

Regards,