You can find and download this sound effect for free from several reputable creative platforms:
Most assets from Mixkit fall under the , which is highly creator-friendly. You can find and download this sound effect
: Perfect for the final "title card" reveal in a movie trailer. You can find and download this sound effect
: Use the swoosh for fast-motion cuts and the heartbeat for slow-motion replays. Download Free Heartbeat Sound Effects - Mixkit You can find and download this sound effect
: The primary source for this file. It is listed under their "Heartbeat" and "Cinematic" categories.