You can follow these to achieve this in Squarespace.
#1. First, you need to create a page in Not Linked with Name/URL
- Name: Site Paragraph
- URL: /site-paragraph
#2. Add desired text to this Site Paragraph page. Something like this.
#3. Edit 100 pages where you want to make this text appear > Add a Code Block
Paste this code into Code Block
<div data-wm-plugin="load" data-target="/site-paragraph"></div>
#4. Install this plugin. The plugin will give you some code to add to the Code Injection Header/Footer.
#5. Done.