Can CRA seize and sell my property to collect unpaid taxes?

Yes, in appropriate circumstances. Once CRA has registered a certificate confirming a tax debt, which has the same effect as a court judgment, as covered in a related question, CRA can proceed to seize and sell property to collect the debt, similar to how any judgment creditor could ultimately enforce a judgment against a debtor's assets.

This is a real and serious enforcement step, but it's generally reserved for unresolved, significant debts rather than something CRA moves to immediately or routinely for every tax debt. There are typically earlier stages of collection activity, requirements to pay, registered certificates, and other administrative measures, that come before an actual seizure and sale of property, so reaching this point usually reflects a debt that has gone unaddressed through those earlier stages, not a first response to a new or modest debt. That said, it's a real possibility and not an empty threat, and the fact that it's usually a later-stage measure doesn't mean it can't happen. If you're facing a significant, unresolved tax debt and are worried about this kind of enforcement, addressing the debt through a payment arrangement or other resolution before it escalates this far is considerably more manageable than dealing with an actual seizure.