This section is available on Kalles, Gecko.
From Theme settings > Other Settings > Turn on "Enable Login sidebar widget" and you can also choose which page to show when customers log in to your online store. If you don't enter the link page, it'll redirect customers to the account page after they login.
Moreover, there are some options in Other settings to config Login feature. You can check this document.
To config Login sidebar, from the Sections Sidebar > you will see the Login Sidebar section.
Note: If you did not turn on the "Enable Login Sidebar widget", the login sidebar will not appear.
Content align: There are 2 types of contents including default and center.
Button options: Helps you configure the style of the button with options for Button width, button style, button size, button color, button hover effect.