The key search words in your (Chinese? better than rewarding Amazon with even more extra fees) store of choice I wound suggest:
3.5" to 5.25" Internal Hard Disk Mount Rubber
But don’t get the ones where the inner mount (of the 3.5" drive) is the same piece or bolted/screwed into the outer mount (5.25").
The ones in my pic have fairy big rubber nips in between (each secured on both sides), 4 at the bottom (that support the weight if the disk too), and two on the sides.
Also such 5" brackets you mount anywhere rally, even on the outside of the case, lol.
In one case without the 5.25" bays (at my parents, quick job) I mounted two disks on such mounts on that metal mesh between the PSU compartment and main compartment.
(Also not change anything besides maybe make a terms upade.)
The horror!!