1. Let's take the following figure as an example. The top size is 300, but the actual size of the drawing is not 300. Enter the sc command with the keyboard.

2. Then select the picture as the zoom object.

3. After selection, the cursor is selected at any point as the base point.

4. At this point, enter r to start the reference zoom command on the keyboard.

5. Use the cursor to select the green marking line with the length of 300 in the drawing, and then use the keyboard to enter 300.

6. Enter and confirm. At this point, the picture will be scaled. Use the di command to measure the green marker line with a length of 300 in the drawing, and then you will find that the measured length tends to 300.