Mavi makes 36 inch inseam denim and the brand just rolled out new washes in straight leg and bootcut styles. Moreover, I found few 38 inch inseam styles on the online store. However the styles that super long length were available in (flare and split hem, Mavi understands proportions), have been sold out.
Below is a round up of 36 inch inseam denim from the United States site and the Canada site.
United States store
Canada store