Google Sheets only does data filters in the browser, their mobile app does not support that feature. Is there another iOS spreadsheet app that does support such a feature? Basically, I want to be able to filter data for a column in a spreadsheet on my iPhone.
Microsoft Excel is available for iOS for free.
Downloading and viewing Excel spreadsheets can be done once it is installed.
Editing (including filtering) can be done if you signed in to Microsoft's service inside the app. You can log out immediately after having logged in, if you prefer not to be signed in.
Some features will not be available until you subscribe to Office 365.