Upvote:1
A letter of invitation is not mandatory - if you don’t have personal connections in Canada then you can’t supply one. What is necessary, in common with visitor visas to pretty much any destination, is being able to convince an immigration officer that you have ties—such as a job, home, financial assets or family—that will take you back to your home country at the end of your visit and that you have enough money for your stay.
https://www.canada.ca/en/immigration-refugees-citizenship/services/visit-canada/eligibility.html