Knocking sound from engine, The car is a Peugeot 308 1.6 THP
Watch the video here
https://www.bilgalleri.dk/video/diverse-bil/61327-tikke_lyd_fra_motorrum
Sounds like a lifter problem.
Not familiar with Peugeot engines but I’d take it to your trusted mechanic.
The valves may need to be adjusted…if they are adjustable.
Yosemite
Sounds like a diesel engine. Is it a diesel? If not, I agree that you need a valve adjustment.
It’s a petrol/benzin car
It sounds like loose rockers (valve adjustment). Loose is usually not a big problem unless it is an exhaust valve that reaches the point where it doesn’t open at all, then it will blow the engine. If you can get the valve cover off, you can feel for any loose rockers by hand, just move then up and down. Most will have a little play but a couple will be tight as they are actuating valves. Rotate the engine and check them again. If you find one that is excessively loose, like greater than 1/8th inch (4mm), then you need to determine if it is exhaust or intake and if exhaust, it must be fixed before any long drive, like ASAP.
It could also be a loose spark plug or an exhaust leak. Pull the SP boots off, one at a time so you don’t get them mixed up and give the plug a twist with you fingers. If it moves, fix ASAP.