you want to check your oil filter, oil quality and level, oil pressure, and crank breather system initially, and don't race the engine until you have had this noise sorted.

The tappets are hydraulic and you can sometimes clear a blockage with an additive then change the oil soon after.

The big ends will take a professional to diagnose, and as the good lady says

- it's a much more pronounced

"knock" like a dull mallet on metal rather than a tinkly lighter sound.

Others will be here soon to help don't worry
