This can be done via BIOS mod to make it visible to you (Dump BIOS region with FPT, modify that, unlock BIOS Lock, reflash BIOS region with FPT), or it you can change the current default option via grub using setup_var

I checked, and xHCI handoff is enabled by default already, so you should be good to go

XHCI Legacy Support, VarStoreInfo (VarOffset/VarName): 0x1A, VarStore: 0x20, QuestionId: 0x388, Size: 1, Min: 0x0, Max 0x1, Step: 0x0 {05 91 6E 0E 6F 0E 88 03 20 00 1A 00 10 10 00 01 00}
One Of Option: Enabled, Value (8 bit): 0x1 (default) {09 07 E2 15 30 00 01}
One Of Option: Disabled, Value (8 bit): 0x0 {09 07 E3 15 00 00 00}

One Of: XHCI Hand-off, VarStoreInfo (VarOffset/VarName): 0x1B, VarStore: 0x20, QuestionId: 0x389, Size: 1, Min: 0x0, Max 0x1, Step: 0x0 {05 91 ED 15 EE 15 89 03 20 00 1B 00 10 10 00 01 00}
One Of Option: Enabled, Value (8 bit): 0x1 {09 07 E2 15 00 00 01}
One Of Option: Disabled, Value (8 bit): 0x0 {09 07 E3 15 00 00 00}
Default: DefaultId: 0x0, Value (8 bit): 0x1 {5B 06 00 00 00 01} << comment below
Default: DefaultId: 0x1, Value (8 bit): 0x1 {5B 06 01 00 00 01} << Both BIOS profiles are set to 0x1 = enabled