What will work better?

Lets say i am targeting a few keywords which are in very correlating subjects.

I am with SEMRush open, so i will throw in an example. lets say i am targeting "On Page SEO"

Now i get all the variations of the keywords and their metrics.

My question is, i better build a post for each of the variations?

Or will it be better to have few bigger articles which will cover few of the topics each?

If i go with the second option, is there a good guide on how to stuff the keywords the right way?

And if i go with the first (post per keyword) way - i assume the keyword should be in the link itself, and in the headline, and stuffed at some density in the text, is that right? i saw also alot of people making that keyword text BOLD

SEO is my Achilles Hill, please bare with me

if they are related, you could try a content hub approach, similar to Backlinko's: https://backlinko.com/hub/content

You can actually copy the whole structure and replace only the content.