I am totally new in the flow topic, so sorry if the question could be "too easy" for you.
I have an existing Sharepoint list with various columns (most important are for the flow columns "alert date" and "responsible")
Many thanks
Harry

Create a New Flow
Get Items from the SharePoint List
Filter Items by Alert Date
Loop Through the Items
value).Send an Email Reminder
item()?['ResponsibleEmail']ResponsibleEmail is the name of the column that contains the person's email address)Example for email body:
Set up the Weekly Reminder
Save and Test the Flow