@sarojgauli00123
"We want to upgrade our Cisco SF-300 24P 10/100 POE Managed Switch to SF-350 24P 10/100. "
300 and 350 are two different devices. What do you mean by upgrade here? Do you mean you are going to replace 300 by another 350?
"Is there an option to backup config from the current switch and just dump in to the new one? "
If I were you, I would try. They are very similar but I did not find any doc to support it.
"Or do we need to configure the new switch with everything from scratch? "
Big chance this end up happening.