What you want to do is find the shortcut that you use to launch Outlook, right-click on it, and then select Properties. This will open a dialog. In the lower half of the dialog you'll see a combo box labelled "Run". That is likely set to minimized. Change it to "Normal Window"
If you open Outlook from the start screen or the task bar, you can't open the shortcuts Properties dialog in the same way.
On the task bar > shift+right-click does the same
On the start screen > right-click and then select Open File Location. That will open the shortcut in File Explorer.