Using a local timezone for the Content Management Explorer in Tridion Sites 9.1 had not been possible, and the server time needed to be referenced instead. As of Sites 9.5 and later product versions, content item timestamps are returned in the local timezone instead of the server timezone for the Content Manager Explorer (CME) and the Experience Space client. So all system dates like created, modified, published, activity assigned/finished, etc. will be displayed in the user timezone for Sites 9.5 and later product versions.
As of Sites 10.0, component date fields and metadata fields do not yet support the UTC format. So these dates are shown in the format that the user enters them. The text "All selected dates and times are Content Manager server dates and times" appearing for the Publish Settings tab of the Publishing queue popup is incorrect and will be removed in a future product release. The timestamps are in the content editor's local timezone.