What things are you trying to do that’s not supported with parcel? I think sometimes we make super complex front end build configurations that don’t yield much benefit over something more simple.
If you're certain it covers all of your requirements out of the box, it's a great option. Otherwise...you're probably better off configuring Webpack from the start. I've never hit an issue with Webpack that can't be solved (an likely it has already been solved by someone else).