From the SQLite documentation:

RTRIM is like BINARY except that extra spaces at the end of either string do not change the result. In other words, strings will compare equal to one another as long as they differ only in the number of spaces at the end.

It's not explicitly said, but trailing tabs should be preserved by RTRIM.

Turso:

turso> select 'x' || char(9) = 'x' collate rtrim;
┌─────────────────────────────────────┐
│ 'x' || char (9) = 'x' COLLATE rtrim │
├─────────────────────────────────────┤
│                                   1 │
└─────────────────────────────────────┘

SQLite:

sqlite> select 'x' || char(9) = 'x' collate rtrim;
0