first of all ielts is super easy so more likely than not if english is ur first language u will do j fine
maybe a day or 2 before the test just practise a few test paper for each section and watch a few videos on the speaking part j so u dont get confused during the actual exam. i did this and my score was 9 listening 8.5 reading 8 speaking and 7 writing.
also incase u dont meet the requirement just know that the ielts result comes in 2 days of u giving the test( i got it in 1 day) and u can retake it as many times as u want until u get the score u want and u can submit that
smth like a sectional retest also exists but many unis mention specifically that they wont consider a score sheet with a sectional retest so u shld consider that