Many 401k plans allow you to contribute non-deductible contributions after the maximum. The backdoor Roth is about $7,000 per year. The non-deductible 401k limit after maxing out is $37,000 minus employer contributions. So, lets say you put in the full $19,000 and with matching and profit sharing, the employer puts in another $6,000. This means you could put in another $31,000 for a total of $56,000. This is NOT a Roth but a non-deductible 401k.
How does this help you? You will not be paying taxes on the earnings of the $31,000 each year.
In addition you could do your backdoor Roth.