Smart bulbs can be used to save energy, help secure your home, turn your basic light switch into a dimmer, or prevent you from being tied down to an inconveniently-located switch. All you have to do is replace the bulbs you already have with smart bulbs.
There is a one-time purchase of a small hub that has to be plugged into the wall and then connected to your router via ethernet, but it takes five minutes to install and can accommodate up to 50 bulbs, meaning you won't have to worry about it again.
You can buy smart bulbs in most locations that sell standard light bulbs. Many smart light bulbs can connect directly to your smart speaker via a separate app, but some smart bulbs require a separate hub, so make sure you're checking the details of each bulb before you buy it. Also, make sure you check to see if the brand is compatible with the smart assistant you have (as you should do with every one of these products moving forward), and then take a look at the size of the bulb you're replacing so you get the right one.
Hue Philips is a popular brand that offers starter kits (bulbs and hub), is compatible with Alexa, Google Assistant, and Siri, and even offers ones that let you set the mood by changing color.