There is currently no easy way to edit EXIF data especially in batch fashion on Mac or iOS devices. Importing photos into your iCloud photo library with incorrect Date Time information can result in the disaster of your photo timeline being bombarded with photos from incorrect dates. I recently had to import a large number of photos into my iCloud photo library and encountered this exact issue. Unfortunately, the date time editing function seen in the Photos App on MacOS and iOS (see image > adjust date and time) does not actually change the original date time for an entire sequence of photos but rather applys an offset resulting in batch edits of photos leading to photos with incorrect timestamps into the future. After trying a multitude of free EXIF editing apps on the Mac App Store which all have paywalls or limits, I stumbled on exiftool, a command line focused tool for batch editing photo files.

Exiftool can be installed via Brew brew install exiftool.

To change the original date time of a large sequence of photos you will want to edit the Date/Time Original metadata tag by using the following command: exiftool "-DateTimeOriginal=YY:MM:DD HH:MM:SS" -r TargetFolder

The tool will change all the exifdata for the files you target and additionally will backup the original file in case errors are encountered. Changes can be viewed by running exiftool -common targetfile.jpg which will output something akin to the following:

File Name                       : file.JPG
File Size                       : 18 MB
Camera Model Name               : ILCE-9
Date/Time Original              : 2020:01:01 07:30:00
Image Size                      : 6000x4000
Quality                         : RAW + Extra Fine
Focal Length                    : 12.0 mm
Shutter Speed                   : 1/100
Aperture                        : 4.0
ISO                             : 1250
White Balance                   : Auto
Flash                           : Off, Did not fire

Enjoy!