VLSI chip design and development

can i specify all the paths as multicycle paths

specifing a path to be a multicycle path is purely a design requirement and it is nothing you can do much on this thought process.

By default, the tools(Synthesis and Static timing analysis) works on single cycle paths .
In case if your design requirement is such you can operate some paths as multicycle paths, please specify this to the tool.

Beaware of setting a path as a multicycle path if you are not sure, as the real violation of timing could be masked and finally could be caught at the Dynamic timing analysis(DTA) with functional simulations. But this could be late!!!

Praise the Lord.