Is there any way for wheelchairs to get on the beach by the water
There's a promenade with steps that are accessible. South end of beach:
You'd need a special wheelchair to roll it on the sand. These exist (especially in the motorized form) but most wheelchairs are not sand friendly. You need wide wheels (and double wheels front and back are better). It would be really hard to push a regular wheelchair through the dry sand section.
Regular wheelchair, No.
However, Avila Beach has a pedestrian friendly promenade that includes a section of the pier where you can roll a regular wheelchair out over the sand. Unfortunately, part of the pier over the water is currently closed.
Another option would be driving to the end of the Hartford Pier west of Avila Beach. That gets you right up to the ocean if wanting to get closer to the water.
As mentioned, it does take a beach wheelchair to maneuver across the sand.
The California Coastal Commission has a nice beach wheelchair resource page. It shows all the locations in California where a free beach wheelchair can be borrowed for access.
On the Central Coast, there are manual beach wheelchairs both Avila and Pismo as well as at Oceano/Grover Beach at the state beach ramp kiosks.
The city of Pismo Beach also has a beach wheelchair that can be borrowed.
I did find a Central Coast company with rental motorized beach wheelchairs that I did not know about. Current cost is $80/day and they will deliver/pickup a chair in Avila, PIsmo, Oceano, and Grover Beach.