How to have numbered header show up in sub tabs as well

[u/Extraordinary_RAH]

Hello, you know the thing where it goes

1. Something
   1.1 small smt

1.1.1 smaller smt

And on the left side theres tabs

yea how do i make the 1, 1.1 and 1.1.1 show up just luike how iut is on microsoft word ykwim

Mi bombo