HTML code to display ?

you can use plugin’s widget or shortcode generator for post/page and then modify yours template to display sidebar with widget or post/page with shortcode.

maybe this will helps https://www.ads-software.com/support/topic/easily-add-widget-areas-to-theme-template-like-blogger-blogspot#post-2828765

ok, it is effectively an solution, but not easy to use.
Somes plugin provide immediatly the HTML code wich is really safer and easyer.
Maybe latter ?

it’s not possible in this case, because there is too many options to set up (so it can be complicated)

ok,