In the Project panel, right-click on the clip you want to modify.
Changing the frame rate of a clip in Premiere Pro allows you to adjust how the clip plays back within your sequence. This can be useful for matching clips with different frame rates or creating slow-motion/fast-motion effects.
When changing the frame rate of a clip, audio is changed in addition to the video. Changing the frame rate proportionally changes the original duration. For example, if you set a 10-second, 24-fps clip to 48 fps, it becomes half as long, with a new duration of 5 seconds.
Change the frame rate of a clip in the Project panel
If you want to change the frame rate of a clip in a sequence, import your media clip and add it to a sequence.
Use this option to change how a clip’s frame rate is interpreted throughout a project. If you want to change only an instance of a clip in the Timeline panel, use the Speed/Duration dialog box to change the frame rate of that individual clip.
Select Modify > Interpret Footage.
In the Interpret Footage tab of the Modify Clip dialog box, select Assume this frame rate and enter the desired frame rate. Note the change in the overall duration of the clip in the Duration field.
Select OK to apply the change.