Hello @Fekadu Deme ,
Welcome to Q&A Forum!
According to my understanding of your question, you want to implement a search function like "Search this library" or "Search this list" on single News Post page.
According to my research, we cannot implement your design in Modern SharePoint Online, it is by design.
Thanks,
Echo Du
===========================================
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.