As a general rule, on arrival to mainland Portugal you don’t have to self-isolate, however, there are a few bits and bobs to consider:
▪️Upon arrival at the airport, your body temperature will be checked.
▪️If your body temperature is normal, you can leave the airport normally.
▪️If your body temperature is high or you show signs of being unwell, you will be referred to the health authorities at the airport (you will need to provide them your contacts and personal information) where you will be subjected to a new body temperature control and you will be required to take a Covid-19 test and to self-isolate at your accommodation until the test results are known.
▪️If the Covid-19 test result is negative, you can enjoy your holidays (although you will still, of course, have to comply with the standard measures in force such as using a mask in certain areas), but if the test is positive you will need to comply with mandatory self-isolation until your flight back home or until a new Covid-19 test shows a negative result.
▪️Anyone arriving from outside the Schengen Area or the EU, must present a negative test to Covid-19 carried out in the last 72 hours. If you don't, and you are Portuguese, you have 48 hours to do so. If you are a foreigner, you need to return home and the airline is fined.
▪️The above refers to mainland Portugal. Madeira and Azores have specific rules.
See more info here:https://www.sns24.gov.pt/tema/doencas-infecciosas/covid-19/prevencao/prevencao-dos-viajantes/viajar-de-e-para-portugal/?fbclid=IwAR3HaynB67IUMY1a2lb9jMzvCFJLhWDWKshZDxECA4aMLa_vyQMCrXpQ8x0