Be aware that most of the vehicle LED festoon bulbs being sold on Ebay have a much lower light output than a standard bulb.
I am comparing White LED, not coloured, as no direct comparison.

Sellers are being economical with the truth describing the item as being made of superbright LEDs.
Whilst each LED has an intensity greater than a standard bulb, that intensity is in a much much smaller area; the overall luminosity is still way less.
A bit like implying a superstrong Ant can lift 10 times its own body weight can therefore lift a house brick!

I have it from a reputable seller of such items that an 18 LED festoon is required to match standard bulbs. Most are 4/6/9 LED.

Based on my testing, I suggest you look at 9 LED versions minimum. Anything else is a false economy (unless you desire lower light levels).

Don't be fooled by photos in adverts showing a brightly lit car interior either - long exposure used to achieve the result.

   < LED/filament bulbs swapped>

W5W (reading light) is an Osram Cool Blue filament bulb - blue coating filters out yellow, bright with a white light.
10W (courtesy light) is a standard 42mm filament festoon bulb, bright with a yellow tint.
6 LED (courtesy light) is in a 42mm festoon package - standard white LED, not warm white, gives a blue tint.

Photos have been resized, but colour, contrast etc. left untouched.
Obviously what exact colours you see depends on how accurate your monitor output is.
Regardless, you can see the differences clearly.