Here are several websites where you will be able to get free downloaded files for your flight simulator. They offer aircrafts, airports, liveries, regions and many other things. Have fun looking through it all!
Ant’s Airplanes
Auscene
Aviation Explorer
Avsim
Bank Angle Studio
Boundless Simulations
Classic British Flight Sim
Devinci Aerospace
Flybywire Simulations
Flysimware
FSDG Online
Fs-Freeware.net
Flight1 File Library System
Flight1 Software
Flightsim.com
Flightsim World
Fly Away
French-VFR
FSX Freeware Sceneries
Gaffer Simulations
Golden Age Simulations
Iblueyonder
Impulse Simulations
IndiaFoxtEcho Visual Simulations
Jar Design (Aéroport Domodedovo for X-Plane)
LHSimulations
Mid-Atlantic Air Museum Simulations
Mirage Aircraft for Flight Simulator
NZA Simulations (MSFS2020)
Onfinal Studio
ORBX (All flight simulators)
Pilot’s (Free repaint for the Majestic Dash-8)
Québec FSX
Restauravia
Return to Misty Moorings
Rikoooo
Roman Design
Sim Heaven (X-Plane)
Simviation
Simzaleak
SOH Combat Flight Center
South Africa for FSX
stuff4fs.com
SurClaro Flight Simulations
The Official Peter Dowson Page
Tropical Repaints
VRoute (50 free routes with the standard edition)
Wolfgang Piper’s Home Page
X-Pilot.com (X-Plane)