Searched for "zwave led dimmer" and this was the first one on the list, recommended by Amazon and works with Alexa.

GE Z-Wave Wireless Smart Lighting Control Smart Dimmer Switch, In-Wall, Includes White & Light Almond Paddles, Works with Amazon Alexa, 12724 https://www.amazon.com/dp/B006LQFHN2/ref=cm_sw_r_cp_api_RDh2ybABD1MGM

Setting up an automation system in your house requires 3 different areas:

1) Controlled "appliances"

2) A hub

3) A controller

I am being specifically vague when I say controlled appliances because this group is vast and varried. You can have smart light bulbs, smart light switches, smart wall outlets, smart thermostats, various sensors, security cameras, and the list goes on and on.

All of these appliances will have a communication system such as z-wave or wifi that allows it to connect to the hub and be controlled virtually.

These can be extremely expensive, but most have gotten relatively cheap. For instance, the light switches I have are about $40 each. So, for about $40 per room you can completely automate the lights of your entire house.

The Hub is simply a device that connects to all of the above appliances and allows you to control them virtually. I have a smartthigns hub. I really like it, but there are several other options that you can use. All have their benefits and drawbacks.

As said above, the main job of the hub is to be the connection/control point for all of your appliances. The secondary bit is that each hub has a control OS that you interface with as a controller for your system. This will take two forms. First form is an app you can install on a tablet or smartphone that will allow you to set up routines or directly control every single connected appliance from wherever you are in the world. The second form (not on every hub) is a simple programming interface that gives you powerful customizing options to how you want to control your system. If you can imagine it (and code it) you can do it, pretty much.

The controller group is also where the echo fits in. You don't need an echo, but it is an amazing addition. Typically having a smart system just meant you could control everything on cool customized timers, virtually from everywhere in the world, and from a centralized "remote" in your house instead of having to go to each device. With the echo you can skip the tablet "remote" all together and just speak to your house and it listens.

I highly recommend diving into the world of an automated system. It is only a couple hundred dollars to get started and you can slowly build your system out over time. Check out /r/homeautomation for some more info too.