One of my kids tried to charge their Kindle Fire with a 8-inch cable that came with some cheap AliExpress gizmo. The cable glowed and then melted. Fun times, since they left it on the couch.
Plain old splitters will almost certainly damage the port, and if this is with a machine where USB-C is part of the motherboard, it could cause even more damage and be really expensive to repair.
The power-only ones are not too pricey. But if you also need high speed data transfer (like drives) those cost a bit more. Be careful that even the ones that claim data exchange may not support drive speeds. It took me three tries to finally find one that worked.