For climate, generally yes: study JRC142832, based on 226 studies, measures an advantage of -4% to -50% depending on the polymer. For other indicators, they often perform worse than fossil plastics because of agricultural biomass production: eutrophication 2 to 4 times higher, land use 1.5 to 3 times higher, and 500 to 1,900 litres of water per kilogram of PLA against around 180 litres for fossil PE. Actual end of life also matters: if the bioplastic is incinerated rather than composted, its climate advantage falls by 30 to 60%.
Read the source article: Bioplastics: market overview and 5 strategic mistakes