Just remember, by using some of new features, they might be not everywhere available, this means some platforms which are WebGL capable, but not ES6 capable won’t run your project.
To check how much of an impact it will make on your audience, it is good to use some generic statistics, for example website https://caniuse.com/
Lets say for Arrow Functions: https://caniuse.com/#search=arrow%20functions ~73% of global browser share is supporting them. Meaning you potentially loos up to 27% of audience.
WebGL (https://caniuse.com/#search=webgl) has around ~92% of global support.
Just make sure this is what you want, as changing back to ES5 is not as easy when project codebase is large.