Chart Widget, set locale timezone to chart

Problem:

I'm designing a timeseries chart using Custom Chart (Chart Widget V 6.3.2). My local client is in UK timezone (UTC+1), but the custom chart datetime x-axis is showing UTC.

For example i feed the dataJson, 2026-08-05T00:00:00.000Z (Date Object).

the chart is showing "2026-08-05 00:00", but i want it to be in UK time "2026-08-05 01:00".

Attempt:

plotly.js/dist/README.md at master · plotly/plotly.js · GitHub

Result:

I purposely add "%Z" to the tickformat to check on the timezone.

Still, it is +0000.

Idea:

1. Adding {"locale": "en"} to the Configuration option doesn't seems to be working.
2. In the case if we need to add other localizations like Swiss-German (de-CH), "plotly-locale-de-ch.js", how can we achieve that?
3. Can we have an dynamic option to select locale based on user's settings/timezone.