It’s three horizontal lines on the top right, by default. Unless you've moved anything, it'll be adjacent to your URL bar. Directly underneath copy, you’ll see a percentage amount surrounded by a - and a + sign.

How would you rephrase that briefly using Vietnamese?
Nhấp vào bảng chọn. Tìm chức năng thu phóng. Nhấp vào dấu - để tiến hành thu nhỏ.