$6,000 is the annual limit on contributions to an IRA. $20,500 is the overall limit on regular elective deferrals 401(k) or similar plan for 2022. It has nothing to do with IRAs. A 401(k) is not an IRA. The limit on regular elective deferral to a 401(k) for 2021 was $19,500. Also, your elective deferrals plus the deductible portion of self-employment taxes is not permitted to exceed your net profit from self-employment.
To be able to make an elective deferral to a 401(k) for 2021, the 401(k) had to have been established and your election made by December 31, 2021. If the 401(k) was established after December 31, 2021, you can still make an employer contribution for 2021 up until the due date of your 2021 tax return. The amount you are eligible to contribute as an employer contribution to the 401(j) is generally the same as the amount that you would be eligible to contribute to a SEP IRA, but may be lower if limited by net profit if you made an elective deferral.
