Simple way to use combo box from Control Toolbox?

If you don't do VBA, you don't want controls from the Control Toolbox. Their ouput is not linked to a cell, they have a click event that you need to process in the appropriate sheet module.

Unless you're ready to learn VBA, stick with the Forms controls.

After adding your combobox to the sheet you need to access it's prperties from the toolbox. You must be in Design View - the setsquare icon.

The Font property allows you to change the font type & clicking the small button to the right gives you more options including size.

The ListFillRange property allows you to define the source, type in the name or address of your range.

To add the selection to a specific cell, as shg says, use the Click event. Click <View Code> & add this

Option Explicit

Private Sub ComboBox1_Change()
'write to A1 of active sheet
Cells(1, 1).Value = Me.ComboBox1.Value
End Sub

The font size of the list in a Forms combobox or list box can be controlled by changing the Style Normal.
Not all of the properties affect the combobox's list, but font name and size can be controlled this way. (The spacing between the lines in the list does not change to fit.)