The 2001 Lexus LS300 does not exist as a distinct model in the U.S. lineup; the 2001 LS models were the LS400 and the LS430, both powered by V8 engines.
Context: the LS lineup in 2001
In North America, Lexus offered two LS versions in 2001: the LS400 (4.0-liter V8, 1UZ-FE) and the LS430 (4.3-liter V8, 1UR-FSE). The LS300 badge was not used on U.S.-market LS sedans that year.
US-market engines in 2001
LS400: 4.0 L V8 (1UZ-FE). LS430: 4.3 L V8 (1UR-FSE). These were the engines associated with the 2001 LS lineup in the United States, making the direct answer straightforward: no LS300 engine in that market for that year.
Notes on non-US markets
Some overseas markets used different badge names or configurations for their Lexus sedans around that era. If you are researching a specific country or a vehicle with the LS300 label, the engine could vary by market and year. Always verify with the VIN, build sheet, or dealership records for the exact engine specification.
Summary
The short answer: there was no engine designated for a 2001 LS300 in the U.S.; the 2001 LS line used the 4.0 L V8 in the LS400 and the 4.3 L V8 in the LS430. International variants with the LS300 badge existed in limited markets and could differ by engine; always confirm the exact engine via official documents.