Smartest way to resize a column?

I am trying to resize a column on a large-ish database (with 5 million rows).

The column was 20 characters before, now I want to make it 35 characters.

Challenge is: this is the main indexed column in a busy database.

I tried looking at the ALTER TABLE commands available and there seems
nothing that allows me to simply change column size from varchar(20)
to varchar(35)?

So I have this in mind:

BEGIN;
ALTER TABLE users ADD COLUMN name_new varchar(35);
UPDATE users SET name_new = name;
ALTER TABLE users DROP COLUMN name;
ALTER TABLE users RENAME COLUMN name_new TO name;
COMMIT;

I guess this would work, but I am wondering if there is a nicer way to
do this that doesn't involve a new column, copying, then dropping old
column?

Thanks!