In Access 2016 application there are such enhancing feature using which you can change the background color of the form using the back color of the property sheet.
Note: you can change background color of different parts of the form. Eg: you can have the form header in one color and the detail section in other.
Go to the left navigation pane and make a right click on the Form and select the Layout View.
Tap anywhere in the form’s detail section to select it. Also an orange border will appear around the section once it is selected.
Click away from the other elements, otherwise you, otherwise it will get selected instead.
From the Design tab, click on the Property Sheet in the ribbon. You can make a right click in the section and select properties.
Using the property sheet change the section color.
Specifically, make use of the back color property to change the background color. You can choose the themes or select a custom color with the color picker.
If you face trouble in finding the right property then click on the format tab to filter the properties to only the formatting properties.