please, help me in this regards i am tiered to find answers from google.
Probably not possible if I think, Because this subdomain is not automatically encrypted like a blogger with Google Trust Services
If you use a paid domain like .com then you can use SSL from Cloudflare or from Let’s Encrypt but unfortunately for Let’s Encrypt is not supported on InfinityFree because for domain verification, robots are not allowed to enter the file manager system.
I’m not an admin, so maybe this opinion could be wrong
You can get a free TLD domain from freenom.com and, change name servers to one of infinity free then, alter the cloudflare option which will enable SSL in your site.