Backlinks for new tool based ( Calculator ) Website

Hi I have create a simple calculator on emd with good volume and getting this results the site is 4 days old and all the pages are index about us privacy policy homepage etc

Now I want to start Off Page so should I start with social signals? but how can i manage the content because this is toool site so i dont have much content

What you guys suggest what type of links should i start first?

Start with profile bulding sites first

For a 4 day old site, I wouldn't be too hasty with the offpage. Social signals are good, but they won't do much for ranking.

Just avoid spam and start with whatever type of links you're planning to build,
It's not like Google will penalize you for having your first link as a comment, PR, contextual, etc...

You'll have less room for the added content,
It's more about authority for such types of websites, you don't have to overthink it

Start building Brand Links initially, you can do it in drip feed. For the content, check your competitors and replicate those topics with some added info if you don't have any clue.