Lots of people upload their research to ResearchGate (even though I really dislike the site for other reasons), make it available from their research group's web page, or in some fields upload it to ArXiv or BioRxiv. It's usually not against the terms of paywalled journals to do any of these things. Google Scholar or even the regular Google search engine can be decent at finding these PDF links. As a last resort, if you're serious about wanting to read a paper, you can contact the corresponding author, who will usually email you a copy and be glad you are interested in his/her work, though this becomes a bit impractical if you need access to multiple references.