auctions-1.0.x-dev/modules/auctions_core/auctions_core.links.action.yml

entity.auction_item.add_form:
  route_name: entity.auction_item.add_form
  title: 'Add Auction Item'
  appears_on:
    - entity.auction_item.collection
entity.auction_bid.add_form:
  route_name: entity.auction_bid.add_form
  title: 'Add Auction Bid'
  appears_on:
    - entity.auction_bid.collection
entity.auction_landing_page.add_form:
  route_name: entity.auction_item.add_form
  title: 'Add Auction Item'
  appears_on:
    - auctions_core.landing_page