Depends, I love building ethno states in it, even if everyone says it’s just a meme.
First higher education can honestly be ignored unless you absolutely need to catchup in tech, if it’s 15-20% it’s ok until after 2020ish, because as it goes up, pop growth goes down, so you want to keep it reasonably low, or else you can drop into negative birth rates, which with enough immigrants you can offset, but it’s still a pain, and will kill and enthostate.
First get nationalists into power, use national focuses to make it so they can’t lose an election, will take a few years. they can give social polices and revoke political policies, which is what you want to create the one party ethno state, pass everything that gives pop growth, you can end up getting it pretty high with Healthcare, Child care, and pensions.
While also revoking upper house reforms until its ruling party only, this will allow you to revoke every polical reform and pass any social reform, until you revoke the final voting reform and become a nationalist dictatorship.
Next get traditionalists into power, and keep them in power long enough to change your national focus to tradition, this gives even more pop growth and lowers war exhaustion and consciousness.
Win wars and purge traitors until over 50% of your pops are traditionalist, will give more modifiers for pop growth. Also during this time amend your constitution to never change from tradition so you can freely swap to nationalist or populist if you need to pass other reforms, without the chance of losing your pop growth.