IPad switching itself off

I bought my Ipad in 2018. It has plenty of spare memory and has been well looked after. It has recently started switching itself off. I have partly fixed the issue by plugging it in to my computer but the recent Itunes update won't install properly. By plugging it into my computer I am able to access the ipad to factory reset it, which means it then limps along for a day before ceasing to work at all again the next day. I've tried following the comands on the apple website etc, but nothing seems to work.