If you're filing e-file, do you have to enter your name on the signature line and date the form?

No, there is no physical signature or date on the tax return when the tax return is e-filed.  The 5 digit self-selected PIN and the 2021 AGI is your electronic signature.

No, it's all done electronically. There's a special pin number for your signature.

I do not think it is possible to enter your name on the signature line and date the form.  When submitting an e-File return the driver license numbers, issue dates and expiration dates confirm who you are and the five-digit code you enter from past years completes the confirmation and this replaces the need to sign and date the form.  If you really wanted to sign and date the return, I think you would have to print, sign, date and then mail via USPS.  Hope this helps.