Why don’t you look for designers and encourage them to design tznius clothes that are both modest and fashionable. Find designers who will design for modest women who will allow women to look like women and feel good about themselves without having a look that entices men. Create clothes that have a modern feel to them (meaning fabrics) and colors that are not ‘boring” and always black, but are youthful for the young, and complimentary to all hair colors and skin colors for various and appropriate ages.
Clothing that is attractive and tznius will give young women a reason to wear it with pride and confidence.