Canon EOS REBEL T7i Instruction Manual page 122

f: Changing the Autofocus OperationN
3 Setting Lens Electronic MF
With the following USM and STM lenses equipped with electronic
manual focusing function, you can set whether to use electronic manual
focusing in One-Shot AF mode. The default setting is [Disable after
One-Shot AF].
EF-S18-135mm f/3.5-5.6 IS USM EF300mm f/2.8L USM
EF50mm f/1.0L USM
EF85mm f/1.2L USM
EF85mm f/1.2L II USM
EF200mm f/1.8L USM
EF-S24mm f/2.8 STM
EF-S10-18mm f/4.5-5.6 IS STM EF-S18-135mm f/3.5-5.6 IS STM EF50mm f/1.8 STM
EF-S18-55mm f/3.5-5.6 IS STM EF-S55-250mm f/4-5.6 IS STM EF24-105mm f/3.5-5.6 IS STM
* As of the product's release date.
Disable after One-Shot AF

Manual focus adjustment after the AF operation is disabled.
Enable after One-Shot AF

You can manually adjust the focus after the AF operation if you keep
holding down the shutter button halfway.
122
EF400mm f/2.8L USM
EF400mm f/2.8L II USM
EF500mm f/4.5L USM
EF600mm f/4L USM
EF-S18-55mm f/4-5.6 IS STM EF40mm f/2.8 STM
Select [Lens electronic MF].
1
Under the [z1] tab, select [Lens

electronic MF], then press <0>.
Set the desired setting.
2
Select the setting, then press <0>.

EF1200mm f/5.6L USM
EF28-80mm f/2.8-4L USM
EF70-300mm f/4-5.6 IS II USM