Hi Andrea,

The verb 'sortir' can be intransitive as in to go out, to leave and it then uses 'être' and the past participle will agree with the subject -

Je suis sorti/e avec mes amis hier soir = I went out with my friends last night 

Nous sommes sortis du cinéma à minuit = We left the cinema at midnight

But it can also be transitive ( has a direct object) meaning to take out /to let out something.

J'ai sorti la poubelle = I took the bin out 

Nous avons sorti le chien dans la nuit = We took the dog out in the night 

Then the rules are like all verbs which take avoir and the past participle will agree or not depending on the position of the object pronoun.

Take a look at the following Kwiziq lesson for further information -

https://progress.lawlessfrench.com/revision/grammar/special-cases-when-the-past-participle-agrees-in-number-and-gender-when-used-with-avoir-in-le-passe-compose-conversational-past

Hope this helps!