Well, for ArchViz stuff, the Architecture template is probably the best start. However, keep in mind, that every template comes with it´s own settings, and that the Architecture contains different things than a Games Template. And as i have mentioned previously, one of those things the Architecture Template brings with it, is a SunSky Actor. And this one contains a Directional Light, that acts as a Sun. And unlike f.e. the standard games light source, this particular Directional Light have it´s intensity pumped up to 75 000 lux (the standard light in games template have just 3.14 lux).
So whatever you do, you have to keep this insane differene in light intensity in mind. Therefore you also need different exposure settings for those different lights.
The moment, you import (or already have by default) a SunSky actor in your scene, you will get one of those mini suns, which will overpower every other light with ease. And if your auto exposure reacts to this directional light, then all way weaker lights will look like, as if they have no or almost no effect on your scene.
Also, as far as i know, nowadays UE4 uses volumetric lightmaps, so you might want learn something about what they are and how they work (they were introduced in UE 4.18):
Here are the Docs for this, maybe you find something helpful in there: