Earlier Blogger only allowed Https redirect for sub-domains(abs.blogspot.com) but now you can enable this feature for your custom domain and make it more secure for your visitors.
So, What is HTTPS & What does it Do?
This protects the visitors from man-in-the-middle attacks, eavesdropping and tampering of the communication.
The main difference between HTTP and HTTPS:
“All communications sent over regular HTTP connections are in ‘plain text’ and can be read by any hacker that manages to break into the connection between your browser and the website.”-Instanssl.com
Here are the Steps to Enable HTTPS Redirect in Blogger for Custom Domain:
2. Scroll down and select HTTPS availability as Yes.
You’ll see the following message:
Wait until the HTTPS Availability is processed. It takes 4-7 minutes.
3. After the processing is complete HTTPS redirect will be available. Select “YES”
Now, all your visitors will be redirected to the HTTPS version of your blog:
Important: Update your link in the Custom Robots.txt file(if you have it enabled), Search Console, AdSense, and every other place.