Can I roll over a 401(k) into a Roth IRA?

Yes, but it’s called a Roth conversion. If your 401(k) is pre-tax, rolling it into a Roth IRA means you’ll owe taxes on the converted amount in the year of transfer. If your 401(k) has Roth contributions, those can be rolled into a Roth IRA tax-free.
This move can be beneficial if you want to consolidate accounts or take advantage of Roth IRA flexibility. However, the tax bill can be significant, so many people plan conversions strategically over several years.