Yes cold emails work.
But they need to be customized for each recipient.
Format it like -
Subject - applying for role | your name
First para - talk about the company applying to and how you can add value to the company with the role you are applying to (customize this)
Second para - details about your work ex/college ex/etc (fixed)
Third para - stuff about how you would love the opportunity, appreciate a reply (fixed)
Sign off
Add link to your portfolio
Use mail merge
Mail merge sheet to have details for 1st para
Best of luck