SharePoint Online-Communication Site- Script Editor apply changes to all pages

[Ricky Raghavan]

I am using a SPFX Script Editor to make color changes on the Header of the Home Page. Now, when I visit other pages in the SharePoint site like-Site Contents, I don't see the changes applied to the header.

How can I ensure that the changes are applied across the site? Is it possible to edit the master page on the Communication site?

[#2]

Instead of using a SPFx WebPart, I would recommend you to create a SPFx Extension