Apparently not, as the Google Translation of a MagX article says that, "...although it was originally planned to appear this summer, it will take time to redesign the exterior and check the reliability of the powertrain, so the debut in spring 2021 is currently planned...
By the way, this Landcruiser 300 was planed to be launched this summer. But due to redesigning the exterior and further develop of the powertrains, it is now delayed until next spring".
The article also states that the Land Cruiser 300 will offer a diesel option in the Japanese market.
was LC300 really supposed to be launched this summer though? If anything, covid-19 would have changed that. Same as with Sienna.
Nobody should launch a new worldwide vehicle in next 6-10 months if they have any smarts in them.