Hello,
It seems you have some questions about the battery life for your Beats and we can help.
If we have a look at the Beats page that quotes the battery life:
Testing conducted by Apple in April 2021 using preproduction Beats Studio Buds and Charging Case units and software paired with iPhone 11 Pro Max units and prerelease software. The playlist consisted of 358 unique audio tracks purchased from the iTunes Store (256-Kbps AAC encoding). Volume was set to 50% and Active Noise Cancellation and Transparency were turned off. Testing consisted of full Beats Studio Buds battery discharge while playing audio until the first Beats Studio Buds stopped playback. With Active Noise Cancellation turned on, listening time was up to 5 hours. Battery life depends on device settings, environment, usage, and many other factors.
https://www.beatsbydre.com/earbuds/studio-buds
So with that information in mind, you could try turning down the volume to 50%, which should get you to about 5 hours listening time with ANC enabled, or you could try turning off ANC and Transparency entirely along with he 50% volume and you'll get closer to the 8 hours figure.
Let us know if that helps.
Thanks for using the Apple Support Communities.