Is it possible to customize a wordpress post without using wp-admin dashboard?
Not the way you’re wanting it, to answer this more thoroughly:
Is it possible to customize a wordpress post from outside dashboard(Something like site.com/post-type/post/?e=post_id)?
Not out of the box, there is no frontend post editing UI in WordPress. You would have to build it yourself ( and many people do )
Can I Build One?
Yes! But you would need to implement the UI yourself, and you would need to process that data and pass it to wp_insert_post, and handle the security.
You could use the REST API, and let that handle the security, simplifying things. That’s what the block editor does.
If so, how do I need to generate url for the post?
As mentioned above, there is no frontend post editing UI out of the box
How to submit the data which is edited through the form?
You’d have to construct the form and the handler for it yourself. wp_insert_post and wp_update_post are the critical functions you need to research, otherwise it’s just like any other form handling.