Do I need to make employee contribution to my solo 401(k) or can I just make the employer contribution?

I have an S Corp and am the only employee of my business. I'm going to set up a solo 401(k) for 2023, and am wondering if I need to contribute as both the employee and employer. If I want, can I just make an employer contribution of 25% of my W2 wages? For example, if my W2 wages are $20,000 can I then contribute $5,000 to my solo 401(k) as the employer without contributing as an employee? I know employee contributions are called "elective deferrals," but want to make sure it wouldn't cause any issues.