I can’t find a post with anyone who’s done this but people say they will fit.

But looking at some websites for parts for a 21 Avalon vs an ES there are suppliers who have struts or coilovers offered for one car but not the other, which suggests they could be different.

Here’s one of the front struts for reference
https://autoparts.toyota.com/products/product/absorber-assy-set-s-485108z344#popup-1

 

Any differences would be tuning to account for weight, characteristics, etc. As far as bolting on, All Camry/Avalon/ES should bolt on to eachother.

So if you installed something from another car, you wouldn't be 100% sure how it would perform. A roll of the dice. Hybrid is a bit heavier in the back too (not sure which ES you have)

 

you’re the only person I’ve seen who says this but without firsthand experience or measurements or side by side photos

 

i can say it. you don't have to believe it. if you don't, you're welcome to do your own research.

you can start with the axle carrier/subframe/crossmember and work your way out from there. camry/avalon/es350/es300h all share. all locating dimensions are identical. the part #s vary due to tuning/characteristics for weight etc. for example dampers will be valved slightly differently. different internal valving/shims for a softer/stiffer ride, depending on need. springs same. different rates.

 

I have retrofitted softer 1997-02 Camry suspension onto the then naturally sportier 1996-01 ES.
The springs are about the same.
Camry roll bar definitely softer with more body roll.
Camry shock absorbers much softer for a lower frequency of vertical oscillations to give a more comfortable ride.

I would be happy to change 7ES with equivalent Avalon springs, shock absorbers and roll bars.
However, I would not recommend swapping Camry for ES suspension due to different wheelbase lengths of the two vehicles.
I also would not recommend swapping hybrid for gasoline model suspension and vice-versa due to differences in weight on the suspension - which may void both warranty and insurance.​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​