A panel upgrade is a job you can read before you sign. The paper should show what is being replaced, what is being added, and who is responsible for each part of the work. Walk the quote the way you would walk the house: slowly, room by room, with your questions written down.
Ask for the load calculation
Ask the electrician to show the load calculation that justifies the new size. It should list the large loads in the house, such as cooking, electric heat or a heat pump, central air, water heating, a clothes dryer, and any planned charger. It should also show the existing circuits that will stay on the new panel. A total with no list behind it is an estimate, not a calculation. Ask to see the list.
Read the service rating and the supply path
Find the amperage rating printed on the existing main breaker and the one in the proposed scope. Ask whether the new rating matches the calculation. Ask whether the service entrance conductors from the meter to the panel are included or left for someone else. Ask who coordinates the disconnect and reconnect with the utility, and whether that visit is priced into the quote.
Check the scope line by line
Look for these lines in the written scope: the main breaker rating, the number of spaces, the bus rating, the grounding and bonding work, the removal and disposal of the old panel, the labeling of each circuit, and an updated directory on the inside of the door. If a line is missing, ask whether it is included or excluded. Excluded lines are where the surprises usually come from.
Ask who pulls the permit
Ask who applies for the permit, who schedules the inspection, and whether you will receive a copy of the sign-off. A permit that is pulled, inspected, and closed out in writing is the record you will want when you sell the house or file paperwork later.
Compare the quotes on the same lines
Put the quotes side by side on the same lines before you look at totals. A lower total with a missing grounding line is a different job from a higher total that includes it. Where a quote skips a line, ask why before you decide.
Log the age of the panel you are replacing
Write down the age of the existing panel and its install year if you can find it. Age is a planning input. It does not tell you the panel is failing. The Electrical Panel: typical service life and when to plan page on this site gives the typical service life and shows how to turn an install year into a planning date.
Read that page with the quote in hand, then check the quote against the lines above.