Like, if I want to add topical relevancy/authority to the page 'domain(dot)com/landing-page'
topical authority means that if you have a site exclusively about cats the "landing-page" in your example should also be about cats instead of snakes or fish. That's all there is to it at the end of the day, you don't need to stress too much over topical authority, especially since it doesn't seem as important as it was...
Also, if I may ask, what are you referring to when you say "landing page"? Because, believe it or not, this term might has different meanings even if, technically, it means the same thing in all situations and - weirdly - it almost always seems to mean the wrong thing
For example, a landing page, in simple (and obvious) terms simply means a page on which your traffic lands. But a lot of people (myself included, in the past) have thought / are thinking that landing pages are pages that have opt-in / subscription forms on them and which are meant to generate leads.
I did use to think this in the past (and I'm ashamed of it, but hey, I was very newbie back then, so don't judge me harshly

), but - as I got deeper into SEO - I've learned that landing pages can be really any page that people land on when they first visit your website, so these pages have almost nothing to do with the type of pages they are (lead generation pages, services / portfolio pages, blog posts, image gallery pages, etc), they can all be landing pages.
But like I said, for my own curiosity, which page were you having in mind when you said "landing-page"?
Still, my answer remains: topical authority means what I explained in the beginning and no matter which type of landing page you are referring to topical authority - most likely - has nothing to do with it
should I create blogs like 'domain(dot)com/landing-page/blog-1', 'domain(dot)com/landing-page/blog-2', etc.
this is so silly, I'd not do it like this even to have a giggle, much less from a SEO perspective
I can just create 'domain(dot)com/blog-1', 'domain(dot)com/blog-2', etc. and then have contextual links to 'domain(dot)com/landing-page'.
this is much better, that's how you should actually do it...
Although, I have to ask again now: when you mention these URL structures, are you simply referring to how these URLs look like? Or are you actually thinking of creating the silos (categories) like this?
Because this might be important as google does read the source code of pages, and if they find a weird structure like in your 1st example - but which you mask this structure with the structure of the 2nd example - then this might be a problem.
Is one method better than the other or will both bring the same results?
I don't think that both methods can bring the same results. I mean, I've not tested this since I've never cared about weird site structures like in your 1st method, but knowing how picky google is I assume that method 2 will work better since it's how google expects to see sites being built...
Which method should I use?
method 2... or other method that's similar to it and which will most likely depend on the topics you wish to cover which will dictate the way in which you structure the site