Minicart Ajax Quantity Increment Decrement
=>Kcn_MinicartQty module has supported in Magento Ver. 2.3.1
=>Kcn_MinicartQty extension has provide functionality to make minicart qty plus minus button using ajax.
=>Customer can easily increment decrement qty through the minicart.
Step 1)First install Kcn_MinicartQty module.
Step 2)Check mincart have two button for qty plus and minus. ---------Done----------------------------------------------------------------------------