Open your design in Canva
Click the image you want to stretch
Drag the corner handles outward to resize the image
Hold Shift while dragging if you want to keep proportions
To stretch without keeping proportions, drag the side handles instead of the corners
If the image is inside a frame, double-click it first, then adjust the crop
Use the Position menu if needed to align the stretched image
Click and drag the image edges if it is placed freely on the canvas
Save or download your design when finished