What does your owners manual say? Mine specifies 0W-20, however it also has this text, "An oil with a higher viscosity (one with a higher value) may be better suited if the vehicle is operated at high speeds, or under extreme load conditions."

Do you regularly operate your vehicle under any of the special conditions listed in the manual? I've taken the hint to use a slightly higher viscosity such as a 5W-30 or 10W-30, especially because of trips from Phoenix to Flagstaff (elevation change 1200 to 7200 feet with grades ranging from 4-6%) at speeds of up to 85 MPH during the hottest days of summer. (Phoenix set new temperature records of 53 days above 110 and 14 days above 115 in 2020.)

If you want more details, consider searching for 1GR-FE posts written by Bryanccfshr on other forums. He lives in Texas and drives under special operating conditions. It appears he knows a lot about engine oils, history of oil specifications and history of Toyota engine design. He doesn’t use 0W-20.