Yes there is, fixed adapter for Schuko to T23. There must be. Exactly because of the case shown here that there are also devices with >10A that are supplied with a Schuko plug. Normally, it is up to the supplier to provide the correct adapter. So that no confusion can arise. You can't tinker with all these devices as you suggest...

https://www.digitec.ch/search

But @Martin1606 will face the next problem as all people who have to use such a fix adapter. You need a socket type 23 (with 16A fuse) as a plug type 23 does not fit into the normal sockets (T12/T13) as these are only designed for max. 10A.

https://www.esti.admin.ch/inhalte...

- - - - - - - - - - - - - - - - -

Digitec (or any other Swiss retailer) is obliged to supply electrical appliances with a Swiss plug. If the appliance is supplied with a foreign plug, a suitable replacement cable should be supplied if the mains cable is pluggable or alternatively if the mains cable is permanently connected, a suitable adapter should be supplied.

If the appliance is delivered without a suitable plug, complain to the customer service and insist on a cable or an adapter, free of charge.

Point 1 --> https://www.esti.admin.ch/de...
Electrical safety --> https://partner.digitecgalaxus.ch/hc...

You won't find a fixed Schuko adapter, if only because of the risk of confusion. 15A is not the power but the fuse rating. How many watts or kW does the thing have? If it doesn't exceed approx. 2.6kW continuously (max. 2.9kW briefly), you can try this (https://www.galaxus.ch/de/s4/product/max-hauri-fixadapter-typ-ef-cee-77-stromadapter-262549).
Otherwise I would "tinker": Buy a coupling (type E+F (CEE 7/7) that fits, short cable approx. 20cm, then a CH plug type. 23, this is designed for 16A. The problem will be that your socket must also be a type 23 and fused for 16A.