Great question Joane! I’m assuming you’re looking to use this as part of a form? If that’s the case, you can totally do that through editing the form fields. 
To do this: 

1. Click on the field you’d like to add a drop down menu to
2. Go to the option “EDIT FIELD”
3. in the FIELD TYPE box, choose a DROPDOWN 

I hope that helps! Let me know if you have any questions :) 

Hi! Thank you for the response. We’re actually gonna use this as like an FAQ type where there are questions and then the explainer/answer for each will be in a collapsible form so that the page will not be too long.

Got it Joane! Would this be helpful: 

Edit: This is a Classic Builder solution and the Smart Builder does not currently offer this as of June 2nd, 2022.

I believe this is possible for the Classic Builder only? I’m using Smart Builder so I don’t think I can add a script to the page I’m creating.

Yes, for the time being that is correct. It is possible only through the Classic Builder. Technically,  there is a way to implement this through your own custom script and add it through the script manager. The other way is if someone builds an app for it in the Smart Builder. For now we don't have a ready-made functionality for collapsible sections. I’ll take this feedback to our product teams, will update you Joane if anything new comes out of it! 

Thank you! Looking forward to more updates and functionality to the Smart builder soon.