If you need to adjust the speed at certain spots in an individual clip, Adobe Premiere Pro’s Time Remapping feature provides an effective solution.
Just right-click your clip, choose “Show Clip Keyframes,” “Time Remapping,” and then “Speed,” and the rubber band becomes visible on your clip. Use the pen tool to create keyframes where speed changes should take effect and use the Selection tool to pull either up (to increase) or down (decrease) the rubber band to bring about desired changes in speed in any section of your clip.
Your clip can benefit from using multiple keyframes and changing its speed in various segments. To provide a smoother transition between speed changes, click and drag the top of any keyframe to form ramps – this helps make changes less abrupt.