If that is the STR10 from 2015, the wheelbase was between 3,100mm and 3,200mm, and an overall length of 5,100mm (per https://en.wikipedia...oro_Rosso_STR10).
The 2017 W08 had a wheelbase of 3,726mm (https://en.wikipedia...1_W08_EQ_Power+) and the W09 was the same (https://en.wikipedia...1_W09_EQ_Power+).
SO there is some scope for shortening the cars.
For 2021 they front tyre width will be reduced, which would allow them to move the weight bias a little to the rear.
I also wonder, what is the effect of the extreme raised nosed of the current cars, combined with the drivers being more laying than sitting i the car? And is the effect significant?
On first sight, it seems to me that both these trends are related. It first started with putting drivers more int a laying position within the car, '86 Brabham and '88 McLaren the pioneers on this trend. Thn you got the trend of raising the nose of the cars to extreme levels, which made it necessary to raise the legs of the drivers ever higher up in the car, thus also forcing them to remain laying in the car.
As a results: Cockpitt volume became longer and due to the rule that the feet of the drivers have to be behind the `front axle line`, that moved the head of the driver more to the rear, potentially lengthening the wheel base.
Reducing/Banning the raised noses and make the drivers sit in the car again might gain a slight reduction of the wheel base.
In the ever continuing story of how ofte aero gain outdoes any handicap of a new construction detail: banning the raised noses could lower the cars in front and bring down the GC of the car. The disadvantage of the higher located GC, introduced due to the raised nose was again more than nullified, if not overwhelmed by the gains thanks to the aero applications it made possible.