Is my phone hacked/ being bugged?

Hi, my sister recently befriended a sophisticated scammer online and her phone, laptop and all my families devices are now unusable. She has had money taken from her bank and the hacker was watching her through the camera. Her phone was visible doing things by itself, opening and closing apps, the same way a screenshare would look without any screen sharing. She says her identity has been sold online (this is all more than I understand) anyway she is concerned as this individual has targeted everyone’s devices included an amazon fire tablet I bought my mum days ago for Christmas that no longer works and that I may also be a target. I don’t live with them and have a different WiFi but I think this is how he has accessed a list of devices and I have used their WiFi before so mine would be on there too. Since all this I have noticed the ‘WiFi call’ symbol where the 4G goes in the top left of my phone when I’m not in a call. This picture shows the symbol but I was not in a call and was unsure why it would say WiFi call when it normally only says WiFi unless I’m actually in a WhatsApp call. I have downloaded Norton spyware but it’s got me worried. Is there anyway to find out if a sophisticated hacker has access to your phone or is listening to you? And if so what can I do? Would changing my Apple ID email and/ or phone number help to make me less accessible to someone like that? Many thanks in advance.