After obtaining a resident visa, you have four months to exchange the resident visa for a resident permit. Yes, you can change employer without losing the right to live in Portugal.
What are the work and residency requirement for work visa holders in Portugal?
If I enter Portugal as a work permit visa holder, how long do I have to wait to get a valid residency card? If I don't want to work for the company who offers me the work permit anymore, can I switch employers without losing my status in Portugal?
As you enter Portugal as a work permit visa holder, you will have to apply for a residence permit for employed workers. This application, on the first stage, is performed online, and, once accepted, you will be asked to schedule an appointment and personally formally submit the application at a SEF (Portuguese Foreigners and Border Services) facility. This whole procedure usually takes around six months to be completed. There may be some delays due to the current pandemic situation. If you wish to switch companies once your residency permit is issued, you’ll be able to do it.