Change Date/Time picker in Service Portal to display the time field without having to select the clock icon.
This Date/Time picker behavior is expected with our Service Portal "out of box" instance. At this time we currently do not have a way of changing the appearance. You can look into the following:
1) You may want to consider posting this issue to our community where professionals, such as yourself, gather to exchange ideas and solutions. There might be a customization option that you may want to try. Please keep in mind that if you do decide to go that route, customizations are not supported by our Support Team.
2) Engaging ServiceNow Professional Services they can assist with implementing customizations, please keep in mind this is a chargeable service.
3) If you feel like this is affecting your environment significantly an enhancement request can be created with our Dev Team so that it may be addressed on a future update.
Create a service catalog variable
Types of Service catalog variables