The Model 3 and the Model Y have basically the same wheelbase of 113" or 2,88 m.
I suppose that the rear seats are about the same distance from the front seat.
One difference is that the Model Y seats can be reclined a little bit.
In the case of the 7 seats, the second row can slide, so it is possble
to move back the second row up to the third row when there is no passengers.
But the big difference is that the front seats of the Model Y are raised up from the floor of about 8".
This gives a lot of clearance to put your feets.
View attachment 851630
In the case of the Model 3, the driver seat is a bout 4' from the floor.
However, the front passenger is only 2" above the floor, may be to give more head room.
So there is very little room to put your feets.