Transfer domain

I am really scared so... I have a domain attached to my website but basically I mucked up with my emails I sent too many too soon now everything goes to spam so I thought maybe I would buy another domain link it to my site so I can get a different Google email... no idea if this was a good idea. So i clicked on Domain transfer which im niw massivly regretting. Now I'm scared that my website URL will change and I really don't want it to! Please can someone reassure me that this won't change the URL of my site I was hoping it would just be an extra site... clearly I don't know what I'm doing 😬