If you are denied to enter US at the port of entry, the airlines which you take to US has the responsibility to take you back to China. This denied entry should not affect your future immigration visa (i.e. green card) application in your case because the denial is not due to crimimal record, overstay > one year in US, or deported out of US before. But you need to report this admission denial in the future visa application and also, bring the copy of the report of the incident, Form I-877 or I-867 (issued by the IO), to the future visa interview.
By the way, you need to read the documents carefully before you sign them at the port of entry including the conversation record between you and the IO, and make sure the conversation record is exact what you said during interaction with the IO.
If the IO allows you to enter US and ask you to go to the immigration court. Then, you lose the case in the court and are deported out of US, normally you will not be allowed to enter US for up to 10 years (case by case) unless you get the waiver later. So, you had better hire an immigration lawyer to help you in the court in this case. Normally you have a good chance to win the case if you show that you have a close connection to US such as you have a family (spouse, kids), a job,, property (e.g house) in US , etc., especially Covid 19 is also a good justification for your delay return to US.
