This Ableton tutorial walks through the full workflow of finding and loading a drum loop using Live 12's browser. After filtering the Samples section by Loop and Drum Loop, clicking any result triggers an instant preview.
If your project is already playing, loop previews automatically sync to your set's tempo, so you can audition samples in context before committing. The Preview and Cue Volume control at the bottom of the main track lets you balance that preview level independently. Once you've found the right sound, drag it directly into your arrangement to load it.