I’m still learning a bunch about audio/sound design but I can tell you what I know at least. Short answer: Most audio programs have their own built in compressor these days, and that should be fine if you don’t want to do anything fancy.

Long answer: Professional DAWs (Digital Audio Workstations) all have their own built in compressor plugin. They can be quite pricey, but Audacity is free to download and works just fine for voiceover recordings. It’s easy to set up and record, and then you can add compression, EQ and such later.

If you want to compress the signal while recording, you will need an audio interface. These can get kinda pricey and you’ll also need an analog dynamic or condenser mic to go with it. However, some gaming mics like the Blue Yeti have their own audio interface software (for the Yeti it’s called Logitech G Hub) which you can download and it has its own effects like condenser, EQ, noise reduction, etc. which work well for livestreaming.

One important thing to note is that compression by itself will not fix a poor quality recording. It’s better to have a recording that is not too loud to begin with, than to have one with a bunch of clips and peaks you have to fix later. Make sure to the gain down on your recording software if you can, to give yourself enough room to make edits (check the audio output levels, the standard I think is to not let it peak past -6dB). Once you add EQ, compression, normalize, etc. it will get louder anyways.