In the Survey123 web designer you can add an 'image' question. At the time of writing this has two configuration options:
There is no option to just 'Browse only'. Survey123 Connect lets you specify 'browse only' mode so it would be a useful addition to the options in the Survey123 web designer.
The use case is if you want someone to upload an image but no give them the option to take a photograph e.g. when submitting a company logo.