Letterboxd has user made lists of upcoming movies, either with dates announced or just announced projects. Fun to flick through and see what directors I enjoy are working on.
I subscribe to the YouTube channels of film and television production studios and often browse my Subscription page instead of the homepage to find videos to watch, I often see trailers there. I also get a bunch of new trailers in my homepage too since I've watched so many.
I found about The Wild Robot movie from a giant billboard on the side of a building at Universal Studios. Since my kids both loved the books, it caught our attention and we looked up the trailer.