How do I transfer just my photos

You can copy your photo library to an external drive and move it between the two devices.

You can use target disk mode (https://support.apple.com/guide/mac-help/transfer-files-mac-computers-target-disk-mode-mchlp1443/mac).

Or, you can enable iCloud photos.

As stated you go to your user/pictures/"photos library" and copy that library folder and then paste into your new Mac at the same location.