Can i post more tags for each post?

No – it’s not true. But posting large numbers of largely irrelevant tags on posts will downgrade the quality of your content from Google’s perspective.

oh So i can post 4-5 tags . & Relative tags of that post posts. That will not effect any right?

4 or 5 tags is fine. ??

I think you have tags confused with keyword stuffing. Ditto on the 4-5 tags being perfectly fine.