As per the Canadian Passport Authority; if you need to apply for your first passport, you will need to provide them with a guarantor and the requirements for the guarantor are that they must have known you for 2+ years and must be Canadian passport holder of 18 years of age or more.

You might run into issues where you are not able to find a guarantor because you have recently moved to a new place within the country and don’t know anyone for more than 2 years. Also there could be other reasons like folks you know might be Canadian Citizens but might not be holding a passport or you might have just not met anyone because of personal/health reasons.

If you don’t know anyone more than 2 years in Canada!
In such a scenario, you can request a Statutory Declaration in Lieu of a Guarantor Form from Service Ontario (or Passport Office). The form is not available online.

You will need to get this form signed by a notary public/justice of the peace/commissioner for oaths. The person signing doesn’t need to know you personally and should not charge you for this.

If you know someone living far away in Canada!
Canada is a big country and driving is not always possible. What you could however do is send out the completed page to your guarantor alongwith your photo and ask them to complete the guarantor’s section for you.

Then they (guarantor) can send the form back to you by mail. I do recommend you to get tracking for your mail and if you are traveling soon then ask them to send it back by expedited mail.

If you are outside Canada
You will need to go to Canadian Consulate or Embassy and request them for a Statutory Declaration in Lieu of Guarantor form. You will need to get the form completed by a Canadian/British diplomat/consular representative; or by a local government official/member of parliament/civil servant.

Expect longer processing time with Statutory Declaration in Lieu of Guarantor
You might be asked to provide more references and if the references are outside Canada then it can take a while for the consulate/embassy to check those details out. It would be ask the Passport Office on processing times so you can plan your trip accordingly!