Hi Chaitanya
We strongly believe in a modular approach. Which can either lead to a prefab “starter Mendix app” as you wish, a Mendix project where you focus on UI/UX and start every project from that particular template. Or, you can create a specifc styling module inside a project and export this to re-use in other projects. Import that .mpk-file to your needs.
Hope this helps!
Kind regards,
Leander