To start setting up the In-Store Pickup functionality within Magento, first please log in to your Magento Admin.
Go to Stores -> Sources:
Click on Add New Source:
To set up your new source, under the General tab -> insert Name -> insert Code (which could be a name, a number, etc.).
Make sure to enable the Use as Pickup Location setting with Yes.
Enter the Contact Info and Address Data details associated with your store.
Under Pickup Location tab -> insert a Frondend Name -> optionally insert a Frontend Description for your pickup location.
Click Save & Continue.
Now go to Stores -> Stocks:
Click on Add New Stock:
Under the General tab insert a Name for the new stock.
Under the Sales Channels tab select one or multiple sales channels for your new stock.
Under Sources -> click on Assign Sources:
Assign the source that was created earlier associated with In-Store Pickup and click Done.
Now go to the Catalog tab -> Products:
Select the products that you would like to transfer from the Default Source to the Destination source.
Click on Actions -> Transfer Inventory To Source and transfer the inventory from the default source to the destination source.
Now go to Stores -> Configuration:
Click on Sales -> Delivery Methods:
Scroll down to the In-Store Delivery section and make sure that the Enabled setting is set to Yes.
When you're done, click Save Config.
To configure In-Store Pickup into WeSupply, please refer to the following article: How to Set Up In-Store Pickup into WeSupply?