Booklet mockup: https://pinspiry.com/a4-brochure-mockup/
Poster mockup: https://www.freepik.com/free-psd/fluid-art-poster-mockup-psd-wall-diy-experimental-art_18764017.htm#query=poster%20mockup&position=3&from_view=keyword&track=ais
No use is allowed without explicit permission from owner