Check out a compilation of free packs from Unreal creators. 

Advanced Vehicle System by Seven47 Software 

A pack for the production of modular vehicles.

Features:

• Physics-based arcade vehicle
• Fully Network Replicated, client authority (Server authority planned)
• Arcade-style engine model (Torque Curve based on air/wheel speed)
• Simple 'Sliding Pillar' suspension model (Advanced suspension models planned)
• Automatic/Manual transmission (no clutch input)
• Wheel locking based on brake pressure and handbrake
• Supports both static and skeletal mesh vehicles
• Built-in functionality for detaching and reattaching wheels at runtime

Hack And Slash FX by pelengami 

Check out cool FX slashes. 

• 10 Unique effects (slashes + impacts) (Plus separate effects versions: only slashes/only impacts )
• Mesh-based slashes (not the AnimTrail)
• Made by using Niagara

Medieval Castle Modular Vol 1 by GameAssetFactory 

Create a medieval castle with modular assets. 

Features:

• Quality assets
• 309 Modular assets
• 9 Pre-Made enclosure walls
• 5 Foliage assets
• PBR Materials
• Vertex Painting
• LODs
• Collisions
• 1 Demo Scene
• Texture Atlas

Office Scene by Jaime Perez 

Grab a collection of office details. 

• Bamboo Pot
• Birdsnest Plant
• 13 Books
• Cabinet
• Ceiling Lamp
• Desk Lamp
• Desk Tray
• 2 Encyclopedias
• 2 Pencils
• Executive Chair
• Executive Desk
• File Folder
• Fountain Pen
• Decorative Metal Globe
• Indoor Plant
• Keyboard
• Laptop
• Monitor
• Mouse
• Mousepad
• Notebook
• Painting
• Pencil Pot
• Plotter
• Printer
• Snake Plant
• 3 Decorative Vases
• Visitor Chair
• Window 

Turn-Based jRPG Template by PhoenixMarket

Check out a blueprint template for RPG games.

Features:

• 100% Blueprints
• Explore / Battle on the same map
• Dynamic camera
• Supportive & offensive skills
• Buffs / Debuffs
• Equipment system
• Show 3D equipment mesh on player units
• Quest system
• Crafting system
• Usable items
• Boss fights
• Save/Load feature
• Item buy/sell vendor
• Mobile/Console support
• Compatible with Conversation2D Plugin

Physical Layout Tool by saeidgholizade

Grab a tool for environment decoration. 

Features:

• Place object physically in map
• Move object with physics enable
• No object intersection
• Paint place object in the map

Check out the Epic Games article on the free Marketplace content to find out more details.