Prophet Muhammad (Peace be upon him) taught us everything even the wonderful dua to wear new clothes.
Dua – 1
أَللّهُمَّ لَكَ الحَمْدُ أنْتَ كَسَوْتَنِيْهِ، أسْأَلُكَ خَيْرَهُ وَخَيْرَ مَا صُنِعَ لَهُ، وَأَعُوْذُ بِكَ مِنْ شَرِّهِ وَشَرِّ مَا صُنِعَ لَهُ
Allāhumma Lakal Hamdu Anta Kasawtanīh, As’aluka Khairahū Wa Khaira Mā Suni’a Lahū, Wa A’ūzu Bika Min Sharrihī Wa Sharri Mā Suni’a Lahū
Meaning: O Allah, praise is to You. You have dressed me. I ask You for its goodness and the goodness of what it is made for. I seek Your protection from its evil and from the evil of what it is created for.
Jame Tirmidhi, Hadith: 1767
Dua – 2
اَلْحَمْدُ لِلَّهِ الَّذِيْ كَسَانِيْ مَا أُوَارِيْ بِهِ عَوْرَتِيْ وَأَتَجَمَّلُ بِهِ فِيْ حَيَاتِيْ
Alhamdu Lillāhillazī Kasānī Mā Uwarī bihī ‘Awratī Wa Atajammalu Bihī Fī Hayātī
Meaning: Praise be to Allah who has clothed me with something to cover my nakedness and beautify myself in my life.
Jame Tirmidhi, Hadith: 3560