Can I open an Individual 401k if I already maxed my Roth IRA?

I am 57. I have: Individual Brokerage account with a small amount of stocks/value in it. Roth IRA with about $85k in it (I started really late!) 401k from my previous employer currently parked at Empower. I cannot contribute to that 401k anymore, and my Roth 401k is maxed so looking for the best way to keep contributing with the best tax implications. These tax implications should cover: Taxes on gains once I retire and need to sell off stocks/etfs for $. Taxes on gains if I need to sell and nee