By default, the Contact Form module allows only the following types of fields:
Input Field - used for regular text such as first name/last name
Email Field - used for entering email address
Text Area - used for Messages, usually long strings of text
Checkboxes - used to create multiple choices where the user can select multiple choices
Radio Buttons - generally used in radio groups—are collections of radio buttons describing related options.
Select Dropdown - generally used to represent a control that provides a menu of options.
To be able to have a date and Time picker inside the Contact Form module, a 3rd party plugin will be required. The plugin used in this article is called Divi Contact Form Helper, and it can be downloaded from Elegant Themes Marketplace.
Adding Date and Time Picker to the Contact Form module using the Divi Contact Form Helper plugin
Download and install the plugin
Edit the Contact Form module
Add a new Field by clicking on the Plus icon
Set the field ID and Label
Note: Make sure the Field ID only contains English characters, without any empty spaces. For the Label, you can use any text you want.
Open the Field Options group and ensure that the Field's type is set to Input Field
Scroll down and open the Date Time Settings
Enable the Use as Date/Time Picker option
Save the Module Settings by clicking on the Green checkmark button.
This is how it will look like on the website, as in the below image:
For a full list of features the Divi Contact Form Helper offers, check the plugin's documentation page.