You can find relevant tutorials on the internet to operate, or go to a professional tailor's shop to ask for changes. If it can't be extended, you can buy a bigger one.

A vest is a collarless and sleeveless short coat. The main function is to keep the front chest and back chest warm and facilitate the activities of hands. You can wear it under your coat or under your underwear. The main varieties are various styles of suit vests, cotton vests, down vests and wool vests. Vests are divided into coats and underwear, and underwear alone refers to sleeveless T-shirts. Suit vest originated in Europe in16th century. It is a collarless sleeveless coat with openings on both sides of the hem, which is about knee-length. It is mainly made of silk and satin, decorated with colorful embroidery lace, and worn between coat and shirt. /kloc-after 0/780, the figure is shortened and a suit is worn. Suit vests are mostly single-breasted and a few are double-breasted or collared. It is characterized in that the front garment piece is made of the same fabric as the suit, the back garment piece is made of the same material as the suit, and the back waist part is also equipped with rings and clips for adjusting tightness.