Tab focus is not working on static objects (Textbox, shape, images) please suggest.

tab will only focus on interactive objects, all non interactive objects will be read by the screen reader in order based on the focus order set in the course. Dependent on the screen reader you may need to use the up and down arrows to read more or access the next object to be read.What you are seeing is expected behaviour. 

I'm glad that Phil was able to help you here, Bhupendra.

Here is some documentation if you or anyone following along would like to take a look:

Storyline 360: Slide Content Is More Accessible

Thank s for information, Phil.