https://help.coinbase.com/en/coinbase/taxes-reports-and-financial-services/taxes/coinbase-tax-resource-center so maybe you better contact them through that since you know they are a professional in that field.
But i think you're not gonna pay for capital gain taxes before you really make the "capital gain" or the profit is still an unrealized profit but i could be wrong, better ask the professional.
Perhaps the op was not aware of this coinbase already made service to make things like buying and selling crypto in the United States much easier even if you have no knowledge about the tax law, it is good you share the information here so that others who are not aware will read this to help them understand it more better.