☕️ TL;DR - You can Split Clips from the Timeline using the scissor button on the Playhead or pressing "C" on your keyboard.
Split Clips on the Main & Source Timeline
Press play or manually move the Playhead on the Timeline to the desired point you want to split the Clip. Press the scissor icon on the Playhead or use the letter "C" on your keyboard to split the Clip. A green label will show at the top confirming your Clip has been split.
NOTE: When you split a Clip, it will split at the point where the Playhead currently is, meaning that the current frame will now be the first frame of the next Clip.
💡 Pro Tip: Zoom into the Source Timeline for a better view of the Clip's Trim region.