Do you want to add search option in Outlook mail and not able to add it and finding it difficult, not to worry here is the full article on How to add search option in Outlook mail where you can easily able to get full understanding of search option in Outlook mail and add search option in your Outlook mail.
Here is the step for How to add search option in Outlook mail?
In the ribbon add a search tab
In Outlook 2016, by default Outlook 2016 hides its advanced search option where you can put a search tab on the ribbon navigation.
On the Outlook ribbon, right click and select customize the ribbon.
Here select home (Mail) in the right-hand list.
Select All Tabs from the “Choose Command” menu.
Select the Search option from the left-hand menu under search tools.
Click the add button.
Now, click “OK”
After clicking on “Ok” the search tab will show in your options button and this “Search Option” will provide such options by subject like sender, attachment and more.
Conclusion: By following this method or steps you can easily get search option in your Outlook mail service