Hi @Muskan Regmi ,
According to my research and testing, there is no out-of-the-box way to display scrolling marquee in SharePoint Online. As a workaround, you can achieve it by coding, please refer to the following steps:
1.Click Page ->> New ->> Wiki Page
2.Click Insert ->> WebPart ->> Media and Content ->> Script Editor ->> Add
3.Click Edit Web Part
4.Click EDIT SNIPPET , then enter the following code,

<marquee width="100px" bgcolor="#cccccc" scrollamount="2" loop="-1">Scrolling Marquee</marquee>
Hope it can help you.
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