https:// at the beginning of URL address, padlock and absence of security warnings in the browser indicate that connection to site is secured by SSL certificate. There are some other options to show that site is secured by SSL certificate. Most widely used one is site seal. Site seal is an image that can be added to web-page for every visitor to see what type of certificate is used and what Certification Authority issued it. At the time being, Sectigo CA provides two types of the Trust Seal: static image displaying the Certificate Authority name, Sectigo, and the clickable Trust Logo that shows the verified company details in the pop-up window.
Here is the Trust Seal for PositiveSSL, and any other DV SSL certificate from Sectigo:
The Trust Logo for the OV and EV SSL certificates will display contact information of company to which the certificate has been issued upon a click on the logo. Here is the example of such logo issued for the EV SSL certificate, installed on Namecheap website:
Please review this article to find more about Trust Logo and its installation.