If client is a business, they should be issuing you a 1099-NEC if they paid you more than $600. These don't need to be mailed until January 31, so you need to wait a few days before filing your return. Clients who are individuals do not have to issue a 1099, but they are allowed to do so voluntarily (most people don't).
You should have your own reliable business records of income and expenses, and report all your income from all your clients, even if some clients don't issue a 1099-NEC.
