where to find good pictures for social media portfolio?

I got a question. Probably a stupid one. I'm trying to create my portfolio with only personal projects since I don't have clients yet. Since I have few social media designs, I was wondering where I could take free license pictures. I already searched on Adobe Stock, Unspash and others, but I seem I can't find anything fitting my idea. I was wondering if it was legal to use Pinterest pictures in my designs writing down in the portfolio a disclaimer I don't own their rights.