is there a way to bulk tag blog posts that I am importing from another site?
and how do we put nav menu to filter posts? is there a way to do it in Duda?
The only way to utilize the nav menu option would be to create custom pages for each Tag you want to display, then on that pay place the Blog Widget with the filter already applied to that widget. So when they click on it in the Nav, they go to the page with the filter in effect.
Unfortunately, manually tagging the blogs is the best way to ensure nothing gets jacked up!
If you need more advanced filtering for your blogs, custom widgets can be used too! You can build one if you have dev chops and otherwise recommend reaching out to Duda Experts for paid solutions :-)