The locked CRV at Curve.fi cannot currently boost LP on Polygon side chains through the user interface, however, Curve.fi will soon be releasing a service that will allow users to boost their LP on side chains. This service will allow users to easily calculate the amount of LP they need to boost in order to receive the best rewards. The calculation will be based on the amount of liquidity the user has in the pool, the length of time the user wants to lock their CRV, and the current liquidity rewards available for the pool. After the user has made these calculations, they will be able to submit the amount of LP they wish to boost and receive the rewards associated with that amount.