Change resistance level for classic trainers

When connecting my classic trainer it uses resistance of 3/10. Is there a way to use a higher resistance so I don’t spin out whenever I try to sprint?

Zwift uses a power curve for classic trainers and the watts are an estimate based on the power curve. So, if Zwift used resistance 3/10 for the power curve then that is all you can use or your watts/power will not be even close to accurate.

Best case, contact support and request they use a new power curve for your brand trainer with a higher resistance setting.