I have radio button selection in mobile app where on selection of it, the dropdown box gets activated. My question is that, is it best practice to place radio button and dropdown in stack manner (pic 1) or horizontal manner(pic 2). If either of them once followed should we have to maintain the same pattern throughout the app or depends on the context?
If you were to follow the principle of progressive disclosure and only showing the information required, you would probably have all the radio buttons grouped together because it is the first action that the user takes. Then depending on which radio button is selected you will have different options displayed for the user to provide further input.
On the other hand, if there is always going to be a dropdown regardless of which radio button is selected (i.e. the next input is of the same data type), then it could be easier to make two dropdowns where you can select from the list of options you already have for the radio button, and then a dropdown for the options that are available based on the first selection.
There is no clear context defined in terms of the overall goal or the design patterns used in the application, so you'll have to make some decisions regarding which design option will provide the most consistent and user-friendly experience.