Dose the 46mm series 10 Apple Watch last long then the 42mm Apple Watch series 10

No. They have the same battery life.

click here ➜ Apple Watch - Battery - Apple

It does not really matter, because you should be charging your Apple Watch every day. The only exceptions being when you are in a situation where your charger is not avaliable, and that should be a rare exception.

If you repeatedly push your Apple Watch so that the battery is drained, you will quickly destroy the Li-Ion battery, and find you are replacing the battery in 1 year.

I charged my Series 4 every night, except for a few exception. My battery lasted me 6 years, and when I traded in my Series 4 it has about 81% battery health, and lasted the rated 18 hours.

I've seen reports in this forum of users that abused their Apple Watch battery and have a battery health lower than 80% in a year or less.

99.99% of what you find online is baloney.