If your students are submitting assignments in Canvas without reading the instructions, you can force them to view an instruction page before reaching the assignment.
To do this, use the Requirements feature of modules. First, create a new module in the course. Next, create a new page in the course that will display the instructions. Type the instructions and any other information the students need to see. Then, return to the Modules area of the course and add the new page, along with your assignment, to the module. Drag and reorder the items so the instructions are listed first.
Next, edit the module (click the 'three dots' in the module header) and click "Add requirement." From the new options,  enable "Students must complete all of these requirements" and  "Students must move through requirements in sequential order." In the item dropdown menu, select your instructions page and then  select "View the item" or "Mark as done" from the accompanying dropdown. Next, click "+ Add requirement",  select your assignment from the item menu, and choose "Submit the assignment" in the accompanying dropdown. Finally,  click "Update Module" to save the changes. Now, students will need to engage with the instructions page before being allowed to visit the assignment page.