I have been accepted for the Master's program in my university and I am currently a Bachelor's program student.

If I were to accept this and change my Bachelor's degree into a Dual BS/MS degree, will my visa be extended or will. I have to apply for a new visa?

If I were to instead choose another university for my master's program and obtain two separate degrees, will that involve a visa extension with a new I-20 or a new visa as well?