AS-02 being ask to supervise

I have been a PS for 3.5 years, and really enjoy my role. Recently the dept I was hired into has slowed down. I have crossed trained in other depts in the past, and have happily been tasked with supporting them part time, taking on both depts and helping with small projects in between. This fills my day with work I enjoy. I am older, and in the private sector I managed a large team in a fast paced environment. But I don’t want to do that now. I love being an admin and have always said I do not want subordinates. Recently I have been told that I will be given a supervisory role for one of the depts I currently support. Do I have to accept? I am not looking to climb the corporate ladder. I am looking to enjoy my work each day and close my laptop at the end of the day without mulling the daily grind over in my mind as I crawl in bed. It almost sounded as though I won’t have a choice the way it was presented. Although I appreciate the offer, it is not part of my career goal. I would remain an AS-02, no promotion. Nothing about it makes me excited. If I accept, can I step away from supervising later? I do know the team, it is very small, and I do like the team. I just don’t want to supervise them! Your thoughts and insight are appreciated! Thanks