This guide shows how to have your player spawn into the game with equipment items (Clothing) equipped.
Go to the BP_PlayerInventoryComponent and then to the Class defaults and search for equipment, this will display all the equipment slot variables.
To set a starting equipment item pick the slot you want to have an item set in, so for this guide I will use the Legs Equipment Slot. First set the ID to the item row name you want to use, so for this I will set it to Cardboard_Pants as this is the row name for cardboard pants. Then set the Count to 1 like the image below shows.