How can you make a small sketch into a large painting, or paint a mural the size of a house? Artists had this problem for centuries. Their solution was to draw a grid.
You can find drawings with grids dating back to the Renaissance. Here is one by Graham Sutherland in the 1940s. He made sketches of thorn trees in Pembrokeshire and enlarged the ones he liked to make big paintings. You can see how he redrew the sketch accurately but changed the colour and some details. The painting is 127cm high. He made other versions too.
To enlarge the tiny drawing he covered it with horizontal, vertical and diagonal lines. He drew the same grid on a much bigger scale for his painting. He could copy the painting one square at a time without any mistakes or distortion.