new phone - don't want photos to disappear

I just upgraded from the iPhone 11Pro to the 12Pro. I need to wipe the 11 clean and I'm concerned it will delete all the photos from the new 12 and my Lightroom Classic on my desktop. 

Is there a way to insure the photos will remain on the new phone? I've paused syncing. I could sign out on that phone. Just not sure.

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