Sensitivity on my iphone XS Max

I have just purchased an iphone xs max today. I went back home and tried typing since I cannot connect to my whatsapp the whole day. Even now, its so hard to type. I had iphone 8 plus before and the sensitivity on typing and touching around phone was superb. It just lag and not so sensitive compared to my iphone 8 plus. I wonder what could be the problem? I bought my phone secondhand from a retailer.