WpRentals has 2 options for guests display. You can use a Classic Guest Dropdown or you can use Advanced Guest Selector. You can control the max number of guests to show in the selector only for the Classic Guest Dropdown option.

Manage Guests as Classic Dropdown

For Classic Guest Dropdown, the number of guests to show can be set from Theme Options.

Go to Theme Options > Booking Configuration > Guest Selector Settings > Enabled advanced guest Control? > No

Below you will see “Maximum Guest Number”

Type the number you wish

The max number of guests set in Theme Options, will apply in the submission form Guest Dropdown too  The number of guests will show in the search form too – if you use the classic guest dropdown The number of guests will show in Booking Form as well

Advanced Guest Selector (Adults/Children Separation)

The Advanced Guest Selector provides separate fields for Adults, Children, and Infants.

If you Enable Advanced Search Control, the number of max guests users can select will NOT consider the guests set in theme options. However, even if search with advanced guest component allows users to select the number of guests they wish, in the property booking form users will not be able to choose more than the max guests you allow and search will not return results if the number of guests does not match what is set to be the number of guests in the property. Ex of how advanced guest works on single property page – booking form