Type To Siri. You will find the “ask siri” option here. Now spotlight integration has been removed, the alternative of having a keyboard shortcut to invoke type to siri is effectively useless if the only way to close it after is using the mouse to click the small 'x' in the banner.
Type your query and tap done. To activate type to siri, head to settings>general>accessibility>siri. Choose don’t speak in silent mode, only speak with hey siri, or always speak responses.
How to use Type to Siri on the iPhone Siri User Guide
Under general tap on accessibility. From now onwards, you can type to siri, instead of speaking to it. How to turn on type to siri open settings and tap on general → accessibility swipe down and tap on siri tap the toggle for type to siri keep in. There, turn on ‘type to siri’.