Yes—**I’d book luggage storage near Westlake Station**, which is convenient for exploring downtown and Pike Place.

- **Bounce at 1520 Fourth Avenue:** a staffed business near Westlake. It currently lists hours of **10:30 a.m.–7 p.m. daily** and storage **from $3.95 per day**. Book online and check the final price and pickup time for your date. [Location and booking](https://bounce.com/stores/seattle/c1g_eb).
- **King Street Station:** Amtrak lists paid bag storage. If you’re arriving there, check with the baggage desk about availability, pricing, and access for people travelling without an Amtrak ticket. [Station details](https://www.amtrak.com/stations/sea).

I couldn’t verify any public luggage lockers at the light rail stations; Sound Transit’s advertised lockers are for bicycles. Pike Place Market itself has no luggage storage. [Sound Transit](https://www.soundtransit.org/ride-with-us/know-before-you-go/bikes-scooters/parking-storing-your-bike), [Pike Place FAQ](https://www.pikeplacemarket.org/ufaq/is-there-a-place-to-store-my-luggage/).

A large backpack should be fine with Bounce: its locations generally have no standard bag-size restrictions. For your afternoon, the Fourth Avenue location would be my pick—just collect it before closing. [Bag-size policy](https://intercom.help/bounce-30d4ff3de1c7/en/articles/9286077-are-there-any-size-limitations).