Dukester wrote:

would western red cedar be strong enough for building a new
chair to the same dimensions as the one made of oak?

For this one? Not a hope. I just don't think you can make a chair from
WRC and use "rectangular spindles" like that without it being either
fragile or looking clumsy. If you use a design based on wide slats then
you could do it in ERC, but even then it's marginal and WRC wouldn't be
up to it. There are similar resinous "outdoor" timbers that are strong
enough and still cheap, but not WRC.