Portfolio Page doesn’t support Masonry Layout, so if you want to make Portfolio Masonry, you can use these options
#Option 1. Add a Gallery Section – Masonry, then enter text/url manually to Portfolio Items
#Option 2. Connect Summary Block with Portfolio Page
It is a bit time-consuming
First, you need to create a blog page with some blog posts (same title as portfolio item)
Next, edit each blog post > enter portfolio item url in Source URL and choose Link Post Title to Source URL (This option means if users click on blog post title, it will open Portfolio Item)
Next, add a Summary Block > Choose the Blog Page you created.
and choose Wall Layout (Wall is similar as Masonry)
#Option 3. Use Portfolio Widget Tool
First, access this link and add some projects
You can also link project item here to Portfolio Page in Squarespace. Thus, when users clicking item on Portfolio Widget, it will open Portfolio Item on Squarespace site.
Next, choose Layout > Masonry
Note, to make item open Portfolio item on Squarespace, you need to click Project > Action on Project Click
and Choose Open Project Website (and set Open in New Tab)
When you’ve done anything, you can click Add to website for free > Choose Free Plan > Copy Embed Code.
Next, edit page where you will place Portfolio Widget > Add a Code Block
Paste embed code
Save and see result