You would need to ensure that the min-width you supply is wide enough for the label the input and the button. All of which will have different widths depending on browser and operating system and users text size settings.
You’d need to explicitly size each of those to be sure they fit within your min-width. In effect your min-width is no different to width as the window will stop it getting larger anyway. It’s just the same as using width in this case.
max-content on the other hand will lay the items out and allow them to take all the width they need. However as I said a line of text will just stretch on forever so you may want to set the max-content on an element that just holds the label, input and button. Let the text run free and it will match the width of the above.
Maybe wrap the form elements in a fieldset and apply a max-content to that instead.