For me it usually completely depends on the project or the depth of the lines/work. Any time I work on commission or am asked to do a paid project, I’ll usually ask them what they were thinking of paying/what their budget is, and if not then I’ll ask for what all they need done, and give a rough estimate based on how long I think that it will take me from start to finish.
I usually go a lot cheaper than these estimates, but this rate sheet from the Global Voice Acting Academy is a great reference material for what a lot of voice actors will expect. I usually shoot for somewhere in the range of $40-$50 per finished minute, or $0.10-$0.15 per word, depending on how the client would rather calculate payment, and adding a little extra if they’d like me to mix things like sound effects, background music, voice effects, and etc.
Honestly though I’m always looking for practice, and I’ll always at least hear a project pitch. If I actively want to be a part of something personally, I won’t always charge for stuff.