you can't e-file with him as a dependent without an SSN for him. even a paper filing with him listed as a dependent without an SSN will delay processing. this leaves you with 2 options. e-file without him (without his SSN your return would be rejected) or wait. It's hard to understand how Covid delayed getting it since he was born in 2019 well before the virus hit.
Do NOT NOT NOT file the return without the SS# and do NOT file without the child ... doing so will mess with your ability to get the CTC, ACTC & EITC. WAIT for the number ... do NOT file yet.