neutral noun "большое пиво" is correct. but it's unnatural expression. we don't use it. better to say "много пива" or "большая бутылка пива"

it's correct suffixes for adjectives in nominative: -ой for masculine -ое for neutral -ая for feminine We usually don't say big beer, we prefer to say big bottle/glass/barrel of beer

because neutral of большой is большое. Nominative case большое пиво, gen.c. большого пива, dat.c. большому пиву, acc.c. большое пиво, instrum. c. большим пивом, prepos.c. о большом пиве.

As in in English, we don't use size with things, which cannot be counted. We use small portion of beer /малую порцию пива/, big bottle of beer /= большую бутылку пива/ end etc. Do mention that russian words here are used in accusative. And ending of adjective depends on the tare