Turn on night light, will yellow stuff.
During the night I usually put my monitor down to 20-30%, it's nice having the option to go higher, and especially useful if there is a lot of light from behind.
In your case I'm pretty sure it's not because the monitor is bigger (though it's a little bit of a factor), it's more that you came from a really bad display to an okay one, the budget monitor segment got a lot better the last 2/3 years and one of the main improvements were most back lights being better/now able to operate at higher nits. I would hazard your old monitor was 200 nits (cd/m^2 of luminance, so how much light per square meter), new one is probably a max of 300 nits. It will probably be something like the new monitor at 50-60% brightness will be the old monitors max since it will have a more even shine.
I suggest you download clickmonitorddc or monitorian (
https://github.com/emoacht/Monitorian) and then quick adjust the brightness as needed between content.
There's more to a monitor than just pixels, color accuracy, ghosting, etc. all matter as well, but yes, I much prefer a 1440p over a 1080p display at 27".