I need to know if the iPhone 8 Plus is funcional in Europe, if I have bought it in Toronto.

LTE Find the right iPhone for the right country or region. - http://www.apple.com/iphone/LTE/

E.g.,

Using American iPhone 5 in Europe - https://discussions.apple.com/thread/4593901 - Yes, but no LTE support.

Some carriers will not accept unlocked phones - https://discussions.apple.com/thread/4530650?answerId=20359060022#20359060022 - E.g., "Virgin Mobile, like all CDMA carriers, will only activate devices on their network that were initially sold for use on their network."

http://www.apple.com/legal/warranty/products/ios-warranty-document-us.html - "IMPORTANT RESTRICTION FOR iPHONE, iPAD AND APPLE TV SERVICE. Apple may restrict warranty service for iPhone, iPad and Apple TV to the country where Apple or its Authorized Distributors originally sold the device." <-- Read this as they almost certainly will refuse to do warranty coverage except where you bought it. The phone would have to be sent to a friend in Canada to handle any repair claims because Apple will not handle international shipping.

Any unlocked iPhone 8 Plus will work in Europe. All Canadian phones sold recently are unlocked.

http://www.cbc.ca/news/business/crtc-wireless-code-cellphone-1.4161711