Is there actually an easy way to sell a “target amount after tax”?

Question is in the title. Let's say, hypothetically, I have a large ETF portfolio and currently need €50k of it. Every share sold is taxed, depending on the price at which I bought it. If I need an exact amount, I have to use an Excel spreadsheet that has all purchases and purchase prices in order to calculate the potential profit and tax for X shares. I can hardly be the first to need this and don't want to believe that this isn't a solved problem