Written with people moving from Turkey in mind. The Portuguese rules still apply more broadly.
The Job Seeker Visa
This visa allows you to enter Portugal specifically to look for work for 120 days, renewable for another 60. You do not need a job offer beforehand, but you must show proof of financial means (3x minimum wage).
If you find a job, you can apply for residency directly from within Portugal. If you fail to secure employment within the validity period, you must leave the country, and you cannot reapply for this specific visa for one year.