I have never deal with the case of SEO before, I found out recently that breadcrumbs have connection with SEO - I would like to use the JSON-LD method - but I do not understand one thing

Question: JSON-LD - generates breadcrum on my page, so i should create correct json code and thats all?

or

i have to generate breadcrum that way i want and google does not care aboute my html, but additionally/separately I have to generate JSON-LD for google support with the same data?

Thanks