Microsoft Office 2016 applications have been designed with touchscreen devices such as tablets in mind
You can enable touch mode in Excel 2016 to optimize all the buttons/toolbars to make them easier to click when using a touchscreen device
To enable this feature click on the down arrow next to the quick launch toolbar (as circled in red below) and click on Touch/Mouse Mode
N.B. This first step may not be necessary as on some devices it automatically detects touch input and enables this option

This will then display a new button on the quick launch toolbar (as circled in red below) where you can switch between Touch and Mouse mode

The images below show the difference between Mouse mode and Touch mode for the Home ribbon - notice how all the buttons are spread out more so you can easily point to them with your finger

