Here is an example on how you can accomplish this.

setting up the data...

drop table if exists account;
create table account
(
    accountid       char(36) not null default '' comment 'key'
  , accountparentid char(36) default null comment 'Id root node'
  , createddate     datetime default null comment 'created date'
  , primary key (accountid)
);


INSERT INTO account VALUES 
 ("1", "null", "2001-01-02"),
 ("2", "1", "2001-02-02"),
 ("3", "2", "2001-03-02"),    
 ("4", "null", "2001-04-02"),
 ("5", "4", "2001-05-02"), 
 ("6", "null", "2001-06-02");


drop procedure if exists proc_account_pagination;

Because your paging based on the parent accounts only, you first need to location the limit and offset of the records in question.

create procedure proc_account_pagination (in p_pagenumber int, in p_pagesize int)
begin
    
    declare v_offset int;
    set v_offset = (p_pagenumber - 1) * p_pagesize;

Then insert those records into a temp table, you can also use an in-line sub query, dealers choice here... (note I'm using ..where accountparentid = 'null' because you're inserting them in your example as char, fixing the data types is recommended :) )

    drop temporary table if exists temp_page;
    create temporary table temp_page
    select
        accountid
      , accountparentid
      , cast(createddate as char(200)) as createddate
      , cast(accountid as char(200))   as path
      , 0                              as depth
    from account
    where accountparentid = 'null'
    limit p_pagesize offset v_offset;

Now run a similar recursive cte to gather the children

    with recursive accounttree
    as
    (
            select
                accountid
              , accountparentid
              , createddate
              , path
              , depth
            from temp_page
            union all
            select
                va.accountid
              , va.accountparentid
              , accounttree.createddate
              , concat(accounttree.path, ',', va.accountid)
              , accounttree.depth + 1
            from account va
                join accounttree
                    on accounttree.accountid = va.accountparentid
    )
    select
        row_number() over (
            order by
            createddate desc) as rowindex
      , accountid
      , accountparentid
      , path
      , depth
    from accounttree
        order by
        path;

end;

And finally test it, good luck!

call proc_account_pagination(1, 3);