You can buy Voice Attack (there's a free trial but limited to ~15 commands IIRC). On its own it won't do much, but you can then install Voice Packs. There's commercial ones (eg, from HCS) as well as free ones (eg, KICS). They may require a greater or lesser effort to configure to your keybinds; I set mine up a very long time ago and heavily customised it at the time so I don't know how easy it is to set up the current crop.
You can also use EDDiscovery (free) which has learned voice commands in the last year or so; personally I haven't used this so don't know how well it works but it seems to autoconfigure based on your current keybindings which is rather nice.
Apart from functionality, which you can probably tweak to be similar no matter what you use, the main difference is that the commercial packs mostly have professionally voice-acted responses whereas free offerings mostly rely on the Windows speech synthesis. Immersive difference.
I use VA (Voice Attack) with a heavily modified version of KICSv3 with bits of KICSv4 thrown in. I also have EDDI running as a VA plugin which adds a tremendous amount of in-game information via voice (handy when flying in VR).
EDIT: PS. HCS currently has a sale on one of their Voice Packs which is voiced by William Shatner for £5, if that's your cup of tea.
Of course, you need some headphones with a good microphone, and depending on whether you use a PC or console, you may not be able to use VoiceAttack.
Since I don't own a console, I'm not sure if you can use it, but on a PC, and using Windows 7/10, you need to train the built in "Text-To-Speech" Voice Recognition (Google for instructions) and train it a few times to insure it will recognize your voice before installing VoiceAttack. VoiceAttack will not work unless you have purchased at least one HCS Voice Pack, usually ASTRA as it can do most of what is available.
Once you get the Windows Speech Recognition trained up, install VoiceAttack, and then install the HCS Voice Pack. Then come back to VoiceAttack and configure all the settings there. Don't worry about the other things mentioned, like EDDiscovery, EDDI or KICS yet, as you need to know how VA and the HCS Voice Packs work first and how to get the Windows Speech Recognition trained up, as well as flying around and giving commands. Once you have mastered this, then you can give EDDiscovery, EDDI add-on and KICS (for music playing and assistance).
It took me a week to get VoiceAttack and HCS Voicepacks working well together and configured correctly, and then a few more weeks to figure out what benefits EDDiscovery, EDDI and KICS offered. Be careful about running too many of these things at once or you will have a cockpit full of voices overtalking each other and your voice commands with not work properly.
Point about the recommendations above about headsets. If, like me, you use a speaker system and wish to keep using it in E D then you need to experiment with microphones to get VA to just respond to your voice and not be confused by the sound from the game. I have loads of microphones so had plenty to choose from, in the end the best results come from using a dynamic microphone - basically like the ones you see used on stage. I find that using condenser microphones should be avoided if you are using speakers as they are far too sensitive.
I agree you don't need HCS - but I can't fly without my crew these days - makes up for the abysmal in-game comms with other players so it is not just for automating game actions. Worth watching for sale promos for them, often 50% or more discounts available.
No doubt there is an obvious answer to this which I have missed or over-thought, so bear with me.... I have gotten an HCS voice pack (well, two, actually). I have set up Voice Attack and trained it. I have a functioning jolly nice headset and microphone. I have installed the Voice Packs into...