Bhavjot
You go to the Settings option, in Domain put your host name, preferably subdomain, and notice that right above the panel,
It has Panel SSl, maybe it is activated or not. save your altar that you made in the host name first, then go back to the panel,
go back to Settings and go to Panel SSL AND ACTIVE, choose the following option SSL Let's Encrypt w Ready.
See here, https://prnt.sc/xx8ct0