Hi @cranium_1 ,
Could you please tell me:
Does a date column already exist in your SharePoint list?
You can create an Edit Form and connect the data source (your SharePoint list) to the Form.
Enter a record in the SharePoint list that you want to change in the Item property.
The Form will generate a DatePicker control in the data card corresponding to the date column, where you can select any date.
Add a Button control and enter the formula in the OnSelect property:
SubmitForm(YourFormName)
The date will be added to the SharePoint list.
I have made a test for your reference:




Best Regards,
Levi