Can the 2020 Toyota Sienna make a U-turn?

Yes. Fits a 40 ft street.

37.4ft curb to curb

Street width, feet

Street 40 feet curb to curb.

2020 Toyota Sienna CE Cargo FWD. Top view, to scale.

2020 Toyota Sienna: turning circle by trim, 40 ft street
Trim	Circle, ft	Margin	One move
CE Cargo FWD	37.4	+2.6 ft	Yes
L FWD	37.5	+2.5 ft	Yes
L FWD 7-Passenger	37.5	+2.5 ft	Yes
LE FWD	37.5	+2.5 ft	Yes
LE FWD 8-Passenger	37.5	+2.5 ft	Yes
LE Mobility 7-Passenger FWD	37.4	+2.6 ft	Yes
LE Mobility FWD 7-Passenger Mobility	37.5	+2.5 ft	Yes
LE AWD 7-Passenger	37.4	+2.6 ft	Yes
SE FWD	37.5	+2.5 ft	Yes
SE FWD 8-Passenger	37.5	+2.5 ft	Yes
XLE FWD	37.5	+2.5 ft	Yes
XLE FWD 8-Passenger	37.5	+2.5 ft	Yes
SE AWD 7-Passenger	37.5	+2.5 ft	Yes
XLE AWD 7-Passenger	37.4	+2.6 ft	Yes
LE 7-Passenger FWD with Auto-Access Seat	37.4	+2.6 ft	Yes
LE Auto Access Seat FWD 7-Passenger	37.5	+2.5 ft	Yes
XLE Premium FWD	37.5	+2.5 ft	Yes
XLE Premium FWD 8-Passenger	37.5	+2.5 ft	Yes
SE Premium FWD	37.5	+2.5 ft	Yes
SE Premium FWD 8-Passenger	37.5	+2.5 ft	Yes
XLE Premium AWD 7-Passenger	37.4	+2.6 ft	Yes
XLE 7-Passenger FWD with Auto-Access Seat	37.4	+2.6 ft	Yes
XLE Auto Access Seat FWD 7-Passenger	37.5	+2.5 ft	Yes
Limited FWD	37.5	+2.5 ft	Yes
Limited FWD 7-Passenger	37.5	+2.5 ft	Yes
SE Premium AWD 7-Passenger	37.5	+2.5 ft	Yes
Limited AWD 7-Passenger	37.4	+2.6 ft	Yes
Limited Premium FWD	37.5	+2.5 ft	Yes
Limited Premium FWD 7-Passenger	37.5	+2.5 ft	Yes
Limited Premium AWD 7-Passenger	37.4	+2.6 ft	Yes

What this cannot tell you

Curb-to-curb turning circle as listed.

Mirrors and overhang need more room.