I feel like I go way overboard tweaking and nitpicking over my drums just to be disappointed with the sound anyway, so maybe don't listen to me.
Idk what kind of beats you make but I strictly sample and make boom bap, so for me I let the sample dictate how the kick is going to sound. If the sample has a lot of low end then I'll use a more thin punchy kick, and if its a lot of high end without much of a low end I'll do something fatter and rounder. If I have a thick bass line I'll peel back the thump on the kick a bit, and if the baseline is more mellow and melded into the sample I'll keep the kick super heavy and loud with some sub bass underneath it.
And I do layer kicks if it needs it. Sometimes after EQing the kick to fit with the sample it loses a bit of its character, so I'll layer it with something else to bring it back. Like if I boost the lowest frequencies on a kick and it starts to wash out its texture, I might track down a kick that's more prominent in the frequencies that are feeling washed out to give it back a similar sound. I usually have to EQ it so only that frequency range is present so it doesn't interfear with the first kick though.
I'm self taught and I don't really know the terms to describe these things, so I hope all of that makes sense.
Here are some things I think you should make sure you understand before you start layering.
M/S Mono/Stereo - Mono your kick and keep as many other elements out of the middle as you can
EQ - Download an EQ guide for bass and kick frequency ranges. Cut or boost those specific ranges and see how the sound changes (bars!).
See how the kick sound changes when you roll off highs. See how it sounds if you cut out some subbass. If you subs are coming from other places or if the track seems to be moving faster than your kick, hi pass the kick at 25hz or 30hz or whatever the standard is for a snappier kick. Change the lo/hi pass filter settings from the 6db filter default. See how making the filter sharper changes the sound.
Envelopes - Play with the kick envelope. If you have a treated kick sample you might have a little extra info at the beginning plus an unnecessary long tail. Or you may just want to fade into the part that pops.
Parallel compression - Before I even try to layer I try out a dry/wet compressor. You can find some compression ratios online & the whatever parallel compressor you're using probably has a kick preset anyway. Just adjust the dry/wet and see how it changes the sound.
Sidechaining/Ducking - I'm lazy with this but this helps makes kicks sound less boring once you get the sound of the kick where you want it. Makes your track less muddy overall.
Saturation - There are decent free vst options, just see how they sound.
Ideally you want to understand all this before you start layering. Don't add a layer of extra sound before you understand what you have. It's a problem I ran into for years when trying to make beats.
The drums typically are the loudest sound in hip hop, but not so much in Rock, and other genres. I will assume you are speaking on hip hop where typically the drum sounds are the loudest. Typically I find that the loudest sound in a hip hop/rap drum mix is the snare drum. Followed by the kick. Everything else typically goes under the drums. as to rather you should layer, it really depends on the sound you currently have, and the sound by which you are going for. There isn't a right or wrong nor rules. Layering is just a technique to achieve a goal. If you feel like you need to add something to a sample/sound that the original sound doesn't have. In that case you just have to figure out what you want to get out of the sound and eq accordingly. As Wizworld said above me there is a lot to consider when it comes to sound design itself.
but Keep it simple, yeah there's a lot of techniques and things to consider, but in the end just worry about making the sound sound good to your ears, Don't try to learn everything at once otherwise you could go down a rabbit whole, and never find the answers you are looking for. Techniques may change, but the goal will always be to get the best sound you can from what you have and the techniques you know. Learn a little everyday to build your knowledge, but don't stress over it. Learn enough to get you to point B, and as you go forward you will learn more in all of those areas that will quicken your sound design in the future.