How to keep updates in a branch only from a specific commit?

Question

git

I have a branch with 5 commits

- function
- test
-amount
-amount
-amount

How can I make from this branch, a branch in which there will be only 1 commit
-function
But updates, so that there are only those that I started making from test
I.e. make a branch test+function->functionthat does not contain everything that I wrote inamout