e-gates are common across many airports in Europe. Essentially, if you have a biometric chip built into your passport and you're using a passport from an eligible country, you'll be able to scan your passport at the e-gates and not need to see an immigration officer.
The gates essentially scan your passport, and scan your face, compare the two, check your passport isn't on a watch-list and then (all being well) the gates open and you're granted entry to the country.
Portugal has made e-gates available to US and Canadian passport holders so you may be able to use them :
https://www.schengenvisainfo.com/new...rom-us-canada/
Some countries restrict use of the gates to persons over a certain age. I have noticed 16 years of age in Amsterdam and 12 years of age in the UK, for example. If travelling with children, you may find you all still need to present to an immigration official.