you can say" is this the required product?" or may i know if this is your required product?

It's okay to say "Could I know if this is your required product?" But more naturally, people will just say "Is this your required product?"

Is it natural to use “ if ' in this sentence? May I ask if this is your required product? / May I ask if you require this product? are both okay. You may use please and kindly interchangeably: Please help me make the sentence better . Kindly help me make the sentence better. We also say "better" instead of "more better".

Thank you very much . I have benefited a lot from your comment .

This brings up an interesting tension between "correct" and "natural". This is correct: "Could you tell me whether this is the product you want?". But native speakers make errors *all the time*, so in fact this sounds more common and natural even though it's incorrect: "Could you tell me if this is the product you want?" Just because there's a perfectly good made-for-the-job word, doesn't mean people will use it. Just like people (at least in my neighborhood) don't use the sidewalk, but choose to walk in the road 90% of the time.