I need answer to update iOS 14 to my mini iPad

Check this link...

Update your iPhone, iPad, or iPod touch - Apple Support

If you have access to a full computer, like a Mac or Windows PC, try either using the Finder on a Mac that has the newest macOS Catalina installed OR with an older Mac with an older Mac OS, download and install the latest iTunes version ( or latest iTunes for Windows PC ), make sure the Mac or Windows PC is connected to the Internet, connect your iPad by the USB charge cable to the computer and let the iTunes application upgrade/update that iPad Mini model, using the iTunes Software Update feature, to its current, maximum OS of iPadOS 14.4.