Depending on your needs, you can change the background color of an Adobe Illustrator project.
Steps

Step 1. Open an Adobe Illustrator file
To do this, double click on the yellow icon containing the letters Have, then click File in the menu bar, located at the top of the window, and finally select To open… Select the file for which you want to change the background color and click on To open.

Step 2. Click File
The button is located in the menu bar at the top of the window.

Step 3. Select Document Format…
The option is near the bottom of the menu.

Step 4. Select the Simulate colored paper check box
It can be found in the section Transparency of the dialog box.

Step 5. Change the first color
Click on the top color sampling box. You will find it in the right part of the section Transparency, right next to the checkerboard image.

Step 6. Select a color
Choose a background color by clicking in the color picker and then adjusting the brightness with the slider on the right.
When you're done, the final color will appear in a preview window at the bottom right of the dialog

Step 7. Save the color
Click on the button Add to custom colors. It will thus be added in one of the boxes intended for personalized colors.

Step 8. Close the dialog box
If you are on Windows, click X, if you are on Mac, click on the red button in the corner of the dialog box.

Step 9. Change the second color
Click on the lower color sampling box. You will find it in the right part of the section Transparency, right next to the checkerboard image.

Step 10. Click on the last custom color
It can be found in the boxes at the bottom left of the dialog box. The color preview at the bottom right will change to the same color as the box you just selected.

Step 11. Close the dialog box
If you are on Windows, click X, if you are on Mac, click on the red button in the corner of the dialog box. The sample boxes and the checkerboard image should be the same color.

Step 12. Click OK
This will close the window of Document format.

Step 13. Click View
The button is located in the menu bar at the top of the window.

Step 14. Click Show Transparency Checkerboard
The option is at the bottom of the drop-down menu. The background will then be the color you selected.