Hi @Rahim Molvani ,
As a short answer, NO. you can't use Office Online in SharePoint 2019, instead, you have to use Office Online Server.
OOS is the recommended solution for integrating Office Online capabilities with SharePoint Server 2019. It allows users to read and edit Microsoft Office documents directly in the browser. Durable Links feature in SharePoint Server 2016 and 2019 requires OOS as a prerequisite.
While Word Online is available in Dropbox, it’s not directly integrated with SharePoint Server 2019. Dropbox provides its own set of features, but it’s not tightly coupled with SharePoint. If you’re looking for seamless integration within your SharePoint environment, OOS remains the better choice.
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.