Hi @JAF,
Could you please share a bit more about your SharePoint list?
Does the Week number column store all weeks number of a year within your SharePoint list?
I have created a SharePoint list on my side and the data structure of it as below:
Note: The Week number column store all week numbers of this year, current week is week 11 of this year. The From date and To date column are both date type column. The Assigned to column is a Person or Group type column.
If the Week number column store all weeks number of a year within your SharePoint list, please take a try with the following workaround:
- Add a Recurrence trigger, Interval set to 1 and Frequency set to Week, On these days field set to Friday.
- Add a "Get items" action, specify Site Address and List Name.
- Add a "Filter array" action, From set to output of "Get items" action, click "Edit in advanced mode", type the following formula:
@equals(item()?['Week_x0020_number'], add(int(div(dayOfYear(utcNow()), 7)), 1))
- Add a "Apply to each" action, input parameter set to output of "Filter array" action.
- Within "Apply to each" action, add a "Send an email" action, To field set to following formula:
item()?['Assigned_x0020_to']?['Email']
Image reference:

The flow works successfully as below:
More details about using expression in flow actions, please check the following article:
https://flow.microsoft.com/en-us/blog/use-expressions-in-actions/
In addition, you could also take a try with the following workaround:
Within Condition box of "Filter array" action, type the following formula:
@and(equals(formatDateTime(addDays(utcNow(), 3), 'MM/dd/yyyy'), formatDateTime(item()?['From_x0020_date'], 'MM/dd/yyyy')),equals(formatDateTime(addDays(utcNow(), 9), 'MM/dd/yyyy'), formatDateTime(item()?['To_x0020_date'], 'MM/dd/yyyy')))
Best regards,
Kris