4000 K is not that bright,
4000K can be arbitrarily bright or dim, because that is the color temperature and not the amount or intensity.
20 W is really not little
20W can be little or a lot, because that does not describe what comes out, but what is consumed.
Of course, these can be exactly the right lamps for you!
For seekers as a mini tip for reading the relevant values
[*]Color temperature - unit Kelvin - High value >4000 similar to midday sun (towards blue) Low value <3000 similar to evening sun (towards orange)
[*]Color rendering accuracy - unit CRI - CRI>90 is considered relatively color-accurate.
[*]Amount of light - unit lumen - amount of emitted light. This is not brightness.
[*]Light intensity - unit candela or lux - intensity of the light
[*]Beam angle - if relevant in degrees - determines intensity of the light in relation to the amount of light
Example: You have 2 LED spots mounted in a room ceiling. Both have the same amount of light - let’s say 1000 lumens. One distributes the light at a 45-degree angle, the other at a 25-degree angle. On the floor, you now have two differently sized light circles. The larger circle is noticeably dimmer than the smaller circle. Same amount of light differently focused produces different light intensity (brightness).
By the way, the efficiency of LEDs (amount of light per watt) decreases in principle with decreasing color temperature and increasing CRI. However, this does not play a significant role in household power consumption.