vocal coach

is it neccessary to get a vocal coach ifyou wanna be a great singer like for musicals and is there limit to how great of a singer you can be

Not all great singers have coaches, but training certainly helps! There's no concrete way to determine your potential when it comes to singing; but we can all improve with practice!

How would you suggest I practice if I dont have vocal coach 

thanks for your reply

Here are some steps to follow! https://www.30daysinger.com/blog/how-to-improve-your-singing-voice-steps-to-follow-for-self-study