Condense Chrome extension buttons

Solution 1:

Resizing the address bar

It seems like you can simply drag your address bar bigger:
A double-arrow appears when hovering over the right edge of the address bar
Then your icons will be collapsed:
The extension icons are collapsed to a little arrow
Source


Hiding single buttons

You can hide single icons, by right-clicking on them and choosing Hide button:
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You can then re-enable the button through the Extensions menu:
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