There are many commercial tours available and places you can visit if you have a car, including:
Wine tasting and cruises
Pinnacles National park
York - Historic town
New Norcia - historic town with monastery and bakery
Some links to consider:
https://www.svtours.com.au/tours/public-tours/
https://www.australianpinnacletours.com.au/
https://www.newnorcia.com.au/visit/visit-new-norcia
You can also catch the train and free bus to the seaside city of Mandurah. approx $10 for train
You can get to many Perth beaches on a bus and Fremantle on the train.
Suggestions are :
Cottesloe, Scarborough Beach, Hillarys Boat Harbour.
If you have a car you can travel along the coast and stop in at different beaches, have lunch etc.
You may be able to find others to join you via the Message board or social media. Be ware that you need to be back in Perth in time if you have booked an evening event.
The pinnacles trip in particular involves a lot of traveling.