Dear Sifus, need some advice here.
I have 2 electrical points in my dining hall, 1 for fan and 1 for downlight.
Similarly there are 2 points in my dry kitchen, 1 for pendant light and 1 for downlight.
Both areas are located next to each other.
At times, I find that the downlight is too bright (18w each). Can I change the downlight switch into dimmer to control the lighting power?
Thank you.

If the LED supports dimming then ok. If not, it will flicker nonstop.

Depends on what type of LED or light being used.

Only those dimmable LED can be dimmed.

LED 18W is not the same as ordinary 18W old type of bulb or energy saving bulb.
The brightness of LED 18W >> 18W energy saving bulb.

So should I change the LED downlight to those dimmable type then I can proceed to change the switch to a dimmer switch?

I learnt something new here. Thank you

On non-dimmable LED, you use dimmable switch has no effect one, I tried if before by replacing a old type of bulb with LED on a dimmable switch supply.

The result, if the switch being set too low, the LED flicker, above certain level, no flicker, but brightness is the same whether set at max or 50%.