Hi Christina,
of course changing the style is possible using SASS and CSS (see this blog http://www.mxblog.nl/2016/03/using-sass-with-mendix/).
By adding labels, you mean adding functionality?
If it is functionality and full flexibility, you could also always create your own custom search, using a searchEntity (or something similar) which acts as a placeholder for your search field(s), and a input parameter for your search (which returns a list for your grid)