Hi @AlbertoSP ,
Could you please share a bit more about your scenario?
Could you please share a whole screenshot about your flow's configuration?
Further, do you submit your SP Calendar items within your PowerApps app, and retrive the corresponding date time value within your flow?
Based on the issue that you mentioned, I think you have faced Time Zone issue. Currently, when working date time values within PowerApps or Microsoft Flow, the date time values would be converted into UTC format automatically.
In addition, the Time Zone of your PowerApps is based on your local time zone in default.
If you want to set the Time Zone for PowerApps dynamically, I afraid that there is no way to achieve your needs in PowerApps currently.
I agree with your thought almost, I think the "Convert time zone" action within Microsoft Flow is good choice for you.
Best regards,