In the Scope panel, issues have a column called "Scheduled start". Unlike "Target start" and "Target end", this does not seem to be editable. Presumably this date is getting pulled from some information on the actual issue - is there a way to change this date?
Have you tried editing the start date of your first or concerned 'Version' resp. 'Release' ?That's accessible via your board, where you can also see your epics.
If you have the dependencies set up properly between your epics and tasks, the 'Scheduled Start' should recalculate to a new date.
So is the answer "no"? There seem to be some things, like the list of sprints that this issue has been in, that are part of the "history" and cannot be changed - is this correct? Thew view for "Scheduled range: Full" is goofy because of this, where something extends back many months just because it has been pushed to future sprints a few times.
The scheduled start and end columns you are mentioning are not part of a Jira issue data and represent the scheduling calculation result. It is not possible to change those currently.
More generally the values given by the calculation are not modifiable as they represent the idealistic dates decided by Portfolio for the data currently in your plan.