dateStyle attribute can be used for lightning:input type=”date” formatting in Salesforce Aura Component. Check the following code for reference.

Sample Code:

Component:

<aura:component implements = "force:appHostable">  	  
	<div class="slds-box slds-theme_default">   		  
		<lightning:input 
			name="input1" 
			label="Enter a date" 
			type="date" 
			dateStyle="short" />  
		<lightning:input 
			name="input2" 
			label="Enter a date" 
			type="date" 
			dateStyle="medium" />  
		<lightning:input 
			name="input3" 
			label="Enter a date" 
			type="date" 
			dateStyle="long" />  		  
	</div>  	  
</aura:component>