Although we are not required to speak with a certain accent, we might feel inclined towards the one we are most familiar with or the one that we enjoy. In the end, it is a matter of personal choice as long as we are understood by most English speakers.
Actors, singers, and TV / radio announcers are sometimes trained to lose their regional accents or to adopt a different one because they are portraying a period character, or to be understood easily by improving their diction. We, as future English teachers, will also need to be easily understood by students. Not to mention that they will look at us as models of pronunciation and diction.
Amy Walker is a prominent YouTuber that explains some of the basics of how to learn any accent. As she said, we have to become truly fascinated with people and the way they speak in order to learn accents. Even if you are not interested in learning a particular accent, I think her explanation can be useful to develop our diction and confidence with the language.
In the video below you can hear her imitation of various accents from different parts of the world.