I'm guessing you mean 12.2s alter table ... modify partition command.
If so, use the update indexes clause to state whether they're local or global. For global indexes, you can use a different partitioning scheme to the base table:
create table t (
c1 int, c2 int, c3 int
);
create index i1 on t ( c1 );
create index i2 on t ( c2 );
create index i3 on t ( c3 );
alter table t
modify partition by range ( c1 )
interval ( 100 ) (
partition p0 values less than ( 101 )
) update indexes (
i1 local,
i2 global,
i3 global
partition by hash ( c3 )
partitions 4
);
select index_name, partitioned
from user_indexes
where table_name = 'T';
INDEX_NAME PARTITIONED
I1 YES
I2 NO
I3 YES
select index_name, partition_name
from user_ind_partitions;
INDEX_NAME PARTITION_NAME
I1 P0
I3 SYS_P2660
I3 SYS_P2661
I3 SYS_P2662
I3 SYS_P2663