To create a Portfolio Page on Squarespace, you can follow these.
Note: The portfolio Page only supports 60 items.
#1. Click on the Plus icon (+) in Not Linked
#2. Scroll down a bit and choose Portfolio
#3 . Then select the Portfolio layout you want
#4. To change the portfolio layout, you can hover on the Portfolio section > EDIT SECTION
Click on Layout – Grid: Overlay
Change to the layout you want
