Yes, you can select this option in your Canvas discussions. However, please note that students may occasionally circumvent this requirement by deleting their posts. To prevent students from being able to use this workaround, you can change your course settings to disable students' ability to delete their posts.

Further resources:

• How can I require students to post to a course discussion before they see replies? Select the Participants must respond to the topic before viewing other replies checkbox.
• How do I allow students to edit and delete their own discussion posts in a course?