How do I transfer my photos from my iPhone 8 Plus to an iPhone 13Pro Max
How do I transfer my photos to my new iPhone 13 Pro Max
iPhone 8 Plus, iOS 14
If they were taken by your iphone 8 and have never been on iCloud Photos or synced with a computer, then any of the transfer methods will move them.
See the instructions in: Transfer data from your previous iOS device to your new iPhone, iPad, or iPod touch - Apple Support
If you do sync or have them in iCloud Photos then re-sync them.