Is it permissible for a woman in the state of ihram to wear the niqab then wear something on the top of it to cover it? لبس النقاب للمرأة المحرمة

All praise is due to Allah alone, and may the Salah and Salam of Allah be upon our Prophet Muhammad, his family and his companions. To answer your question, we say while seeking the success from Allah: It appears to me that this is a way to circumvent the ruling disallowing the woman to wear the niqab while she is in the state of ihram based on the statement of the Prophet (may the Salah and Salam of Allah be upon him) wherein he said: “Women must not wear the niqab [during the state of ihram].” To elaborate in an example, if a man wears the clothes of ihram and underneath he is wearing a pant and a shirt, he has to remove all the sewed clothing he is wearing, e.g. shirts, pants etc., and only keep the two pieces of cloth that comprise the ihram. Similarly, a woman cannot wear gloves and then hide her hands inside her abaya, because the command is not asking women to hide their gloves, but rather it prevents them from wearing gloves, per se, but allows them to cover their hands with anything else.  The same applies to wearing the niqab i.e. women must not wear the niqab to cover their faces, but rather should cover their faces with something else.   That being said, you should know that wearing the niqab while covering it with another layer does not change the ruling of its impermissibility because it would be similar to the case of the man wearing normal clothes beneath the two pieces of the ihram clothes.