Hi David,
If the form is created from Connect, the default map will be set from Connect>Settings>Map>Basemap selector icon. However, this setting will only be honored in :field app," but not web form.
If the form is created from survey123 web, you can set the default map as following, but this setting will only be honored by web form, but not field app.
To answer your question:
<but am I able to change any settings in web Survey123 if I created form in Connect?>
You could change the basemap map manually from the basemap gallery on the web form.
However, this is one time change only, not the default setting you will see everytime when you open the web form.
We are still working on the enhancement ENH-000124977 to have the default map setting honor by both field app and web form.
Hope this helps to clearify your question.