Hi @Adelson Cabral de Sena ,
As of now SharePoint Online only supports maximum three columns section on modern pages.
But if you want to add 4th section on your page, you can leverage the vertical section in SharePoint Online.
Add a vertical section:
Go to the page where you want to add a vertical section.
If you're not in edit mode already, click Edit at the top right of the page.
Hover your mouse below the title area of the page to the far left, or above or below an existing web part to the far left of the page, and you'll see a line with a circled +, like this with a tool tip that says Add a new section.
Click +.
Under Section layout, select Vertical section.
Reference: Add sections and columns on a SharePoint modern page
Notes:
- Vertical sections are currently available only on the right side of the page.
- Length of vertical sections is adjusted based on the content on the page, growing or shrinking with the length of content in non-vertical sections.
- You cannot have a full-width column and a vertical section on the same page.
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