Hi Dmitryl,
You keep asking what exact commands/variables to use, but you have not mentioned which tool you are using inorder to tell you exactly the commands/settings necessary to enable SI analysis. Please be specific.
Assuming that you are using Synopsys Primetime, the setting that you need to use is
set si_enable_analysis true
Yes, you can generate timing reports with and without SI effects. If you do a "set si_enable_analysis false" and run then run report_timing, you will get timing reports without SI effects.
Different tools will have different variables that need to be set. If you are using cadence, there will be some other similar variable which I don't know. I believe that the specific settings for SI analysis are clearly mentioned in Primetime User Guide, so please read it. Likewise I think that other EDA tools will also have similar user guides, so please go through them as there will be a few other filter settings that you need to understand to get good results. You can also use in built man pages for the other xtalk/filter settings.