There is nothing wrong with the husband referred to here consulting doctors for a prescription that will enlarge his penis, so long as there are no harmful side effects.
There is nothing wrong with him using something that is placed over his penis, such as a condom and the like, if that will make his wife’s pleasure more complete, because the basic principle is that it is permissible and the husband is required to treat his wife well, which includes keeping his wife chaste and fulfilling her desires, and removing any obstacles that might prevent that.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said in one of his answers: As for you saying “There is no shyness in religion,” it is better to say that Allaah is not shy to speak the truth, as Umm Sulaym (may Allaah have mercy on her) said: “O Messenger of Allaah, Allaah is not shy to speak the truth. Does a woman have to do ghusl if she has a wet dream?” As for saying “there is no shyness in religion”, this is based on a misunderstanding of the proper meaning. The Prophet (peace and blessings of Allaah be upon him) said: “Shyness is part of faith.” So shyness in religion is part of faith, but when someone says “There is no shyness in religion,” what he means is that there is no shyness in matters of religion, i.e., in asking about something concerning which one may feel shy. If this is what is meant, then it is better to say that Allaah is not shy to speak the truth. Al-Liqa’ al-Shahri (37/25)
And Allaah knows best.