Here you can have a look on how the elements are designed. You can change it via Styles ->Application in the studio, or you can change it in the original file, but than it's changed for all the experiences you make!
Also make sure, to create a copy of the original file before you play around.
I want to mention that for such chang in the environment it is not guaranteed that this functionality will remains the same so that ptc development could change this in future release , but so far is works we can use it…
Regarding to the widget I want here to mention that all widget's created in View could be found in the viewname.json and the script's in the viewname.js in the projectName\src\phone\components directory. Example:
So that theoretical it is possible to read properties from there or to generate widget or to edit widget in this files manually - so far studio is not opened.
Also we can see the definition of the all services which are defined on the external data UI section or as UI twx app events - in the file e.g. MyTestProject\src\shared\components\Data.json
The style definition are in the file e.g. MyTestProject\src\shared\styles\app.scss
So this means we can edit and modify a lot of the project component manually or by customized programing code – which could be helpful when we design a project form templates using some automatic workflow but it is recommended to use the UI if possible because in some cases after incorrect manually modifications we could have a project corruption which will be very difficult to be fixed