Can these values ​​be customized, where can I set it?

Do you need to hold all of the modifier keys, @dublove? Doesn't it work by just pressing Alt while using the mouse scroll wheel?

Here is a link to the various magification techniques: https://helpx.adobe.com/indesign/using/viewing-workspace.html

~Barb

Hi @dublove :

I have InDesign 17.4.2, 18.5.3, 19.4 (and just updated to 19.5 to test) and the Beta installed. All list 50%, 75% and 100%. None offer 80% in the list, nor can we customize the list. As per John and Bill, typing a value works in all versions but if you want to use a key command, I'd say Robert's answer is your best bet. 

~Barb

@dublove

You can create a script - set any value you want or increase / decrease - and assign a shortcut to it. 

Double-click on the 75% in the bottom left of your screenshot and then type whatever value you want and then click the enter key. It's live text.

You can always just type it in the field instead of hitting the arrow.

I remember when I asked a similar question last time, I could jump directly from 100% to 80%. After the new version of 19.5, I can only jump to 75%.

By @dublove

It's the same in 19.4. So if there was a change then it didn't happen in 19.5.