It would be incredibly handy to be able to select a bunch of keys in a timeline and then scale them. Sometimes you’ve got the values exactly where you want them but the timing is a bit off and being able to scale them out (with percentage snapping) would save a ton of time.
Have you tried Ctrl-M? That bring up a little input box where you can transform the selected keys or sections. You can use the * and / to adjust the keys pivoting about the current time.
There’s another way to do this interactively but it’s a bit hidden. If you right click on the track area (it’s actually called a section), then toggle off Properties->IsInfinite. You’ll see bounds appear on that track area. You can adjust those bounds by dragging their ends, if you drag past a keyframe, it won’t delete the keyframe, it just gets clipped and doesn’t evaluate. If you hold down ctrl and drag one of the ends, you’ll actually be able to scale the keys in that section.
Hope one of those works for your situation.
The ctrl + m command is doing nothing for me on 4.19.
If the shortcut doesn’t work, you can always find the “Transform Selection” tool in the “Select/Edit Options” menu:
Once opened, it will display this little toolbox at the top-left corner of the sequencer, next to the tracklist:
It can either “offset” or “scale” your selected keys. You just have to write the amount of offset/scale you want, and click the corresponding button to do the action. ( + and - are for positive/negative offset, * and / are to multiply or divide the scale).
In my screenshot, I “multiplied” the selected key’s scale by two.