Usually 8×4 ply is available in maket., you can opt for century ply or greenlam

It is better if you will use HDMR instead of ply.
Also you can use prelam HDMR.

Plywood is not a good option
go for quality real wood always better option
you can create anything out of it
no matter design is modern or classic
real wood is eco friendly and easy to maintain
plywood I would not recommend.
hope it helps.
sharing current pictures of site for your help

Ishita,

Plywoods are available in 84 ft and 74 ft sizes. These are standard sizes and few exceptions are there.

Thanks,
Nitin
Cornerstone Designs Bangalore

8x4 and 7x4