If any product in the market already and I do some amendment so it is necessary to take patent or not.. It's OK with ur new product to sell in market

I worked for a small logistics company that was developing a proprietary database which was to be packaged like a product. So as the head of HR I ended up doing the research on Trademarks & Patenting.
To answer your question if you have a unique product or a unique take on a product you SHOULD patent it. Ultimately the Patent & Trademark Office will determine if the product is unique enough in its category to approve your patent. I recommend making a few distinct versions even if the differences across systems/products are minimal. If your product is distinct enough to get through the Patent Office but somehow not distinct enough according to the Maker of the original product they might try and sue you. I recommend looking at the slight patent differences between vacuums, mops, and kitchen appliances. There are hundreds of versions of these products on the market and even accessory products. So maybe you could take a product and think of an attachment that could compliment the generic version of the product. Think of changes like the ones you see in those patents to alter the product you're interested in and it should be unique enough to be considered it's own product.
There are lots of free tools available to help you draft your Patent application if you're worried about that. I've popped a few into a PDF which you can find using this shortened link https://bit.ly/3hDzZGf