Hi LMS-8913,
I guess you're using Edge Chromium. Correct me if I guess wrong. The group policies about new tab setting are all in Startup, home page and new tab page.
For now, you can only disable background image in new tab using GPO. You can set this policy Configure the background types allowed for the new tab page layout to DisableAll (3) to disable all background image types. Please notice that this policy only support Edge version 86 or later.
For quick links, you can only edit the links with policy Set new tab page quick links but you can't disable it using GPO. For content, there's no related GPO we can use.
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Regards,
Yu Zhou