On the Share As Web Layer pane > Configuration tab, set both Time zone of the data and Preferred time zone for display to the same time zone. For existing services, overwrite the service and set both options accordingly.
Refer to https://support.esri.com/en-us/knowledge-base/how-to-publish-a-feature-service-with-a-preferred-time--000024927 for more information and use updateDefinition to apply the desired time zone on the layer.