Power Sequencer is an add-on to help you edit your videos faster in the Video Sequencer. It adds many features to help you cut, trim, select, concatenate, or add transitions between sequences.
Open Blender and go to the Edit menu and select Preferences.
In the Blender Preferences window, click on the the Add-ons tab on the left.
In the search bar in the top-right, type "Power Sequencer".
Click the checkbox to the left of Sequencer: Power Sequencer to activate the add-on.
You can find the add-on's full documentation on the author's website:
Video editing tools for content creators.
This add-on is bundled with Blender.