Cmd + / (slash) is the shortcut to show your sequence in its entirety. It fits the sequence to the timeline window adding a bit of empty space (not filler space) after the last clip.
The option Show Entire Sequence is also accessible from the Fast Menu. Its button, called the Hamburger by some, is placed at the bottom left corner of the timeline window.
It does work when you are either zoomed in or zoomed out but does not allow to come back to the original zoom level; it has to be done manually.
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