Hello!
By default, when you drag a clip onto the timeline, you have the ability to change its opacity by sliding the white bar (on the clip) up and down. If you right click the, "FX" button, though, you can change what the slider modifies.
One of those options is Time Remapping (Speed). With my work, I do an extensive amount of speed ramping, resulting in me using the above feature for basically every clip. I would love to see a setting implemented where 'Speed' could be a default slider option over 'Opacity'.