Batch edit pages on website

I have about 100-150 pages on my website, mostly client galleries. Many of these include a message with my phone number, Instagram, and other business details. I recently changed my business phone number and need to update it across all pages. Manually editing each one is too time-consuming.

I’m looking for a way to update these details in bulk, not just for the phone number but for other messages in the future as well. Ideally, this could be done with access to the HTML files or some bulk editing feature.

Additionally, I often need to re-upload photos to these galleries. Right now, I have to delete the images and galleries manually before re-adding them, which is tedious. If I could just edit the HTML to point to the new files, it would be much simpler.

Is there a way to do this efficiently on Squarespace? Any advice would be helpful.