One of my friends does LAX-EDI twice a year. For the trip in Sept, he's doing LAX-YYZ-EDI - Air Canada.

Air Canada is using a 777 on some LAX-YYZ flights, and the YYZ-EDI flight is a 787. It is a SEASONAL flight so as the summer schedule ends, it will likely end too. The outbound layover is 2hr 45 if you take the 11AM aprox LAX-YYX flight and NO security rescreening is needed at YYZ. I would suggest to ensure the RETURN flight though is 3hr + for connections as CBSA (Canada Border Services Agency) has gotten better in the last 60 days but assume 1 hour at least, though it can be quicker.

Canada requires a PCR test for ARRIVALS if NOT vaccinated, but otherwise if vaccinated nothing - if you are the latter a transit within 24 hours remaining in the terminal negates that as well.