Under the Options column > Text Options, the base (XS) alignment allows you to choose left justified, center justified, right justified, and justified. But when expanded to show SM, MD, LG and XL options, only left, center and right are available. There should also be a justified button option for each of these sizes.
Generally, you don't use justified at (XS) mobile size anyway, because it leaves lots of large white gaps between words. Justified is more appropriate for MD screens and up.
I realize you can do this with CSS and media queries, but it would be a whole lot easier to just have the fourth button added to all the screen sizes.
I am afraid this won't be possible to add - in Bootstrap 4 there isn't a responsive version of justify. Not sure what the justification is (pun intended) to have only one size, but it would be nice if they added support for this in the next framework versions.
@Martin, I realize that this app is focused primarily on Bootstrap structure, but when there are things like this thread's request for basic settings that should exist, isn't there any room for straying the path just a bit? I mean, this is a basic text setting that should be able to be applied in some way regardless of whether Bootstrap has that feature or not.
I guess what I'm trying to say is, there are many basic settings that should be included whether Bootstrap has it or not. As you just pointed out basically, Bootstrap is not all inclusive, but as web designers/developers we still need to be able to do things if it's not included. Don't get me wrong, I'm not saying every little strange thing should be added lol, but basic settings like this should be in my opinion. We shouldn't have to find work arounds for text settings.
As @Jo said, some features that aren't strictly in the Bootstrap framework, but that would make this program unique, and make it that much better a piece of software in terms of website builders. But I realize it would require custom programming which then might end up being superfluous/deprecated if a new version of Bootstrap changes things. I guess it's a trade-off we have to live with to use Bootstrap.
Also keeping in mind that yes, some things do become Deprecated at some point, but it's not like we don't find out about it very quickly and you have quite a few users that can keep you abreast of any changes to default code situations. And it's not like it happens every month or year even.
Since Bootstrap comprises of basically making shortcuts for creating components and settings, all it would take would be to utilize default/core CSS to create this or other setups. Even if Bootstrap changes something or deprecates something for Bootstrap, if you use the core CSS rather than Bootstrap to create something for, in this case, being able to have text auto resize, it's not going to go away anytime soon and it will always be compatible with Bootstrap, and no extra files are even needed to accommodate this. Just some food for thought there.