Can you confirm your stated information. Operating system iOS (- not many Mac users on this forum, that might be a problem) Gimp version 3 ( I do not think so)
Best try and forget how PS works, Gimp might get a similar result but in very different ways.
magnetic laso Might be the intelligent scissors tool see: https://docs.gimp.org/2.10/en/gimp-tool-iscissors.html
quick mask For making a selection?
Bottom of the select menu Toggle Quick Mask or shift-Q Toggle-on, paint in white to add a selection, paint black to remove selection. Toggle off. see: https://docs.gimp.org/2.10/en/gimp-image...utton.html
but...there are also layer masks which are different again. An example here: https://patdavid.net/2011/10/getting-aro...masks.html
Best try and forget how PS works, Gimp might get a similar result but in very different ways.
magnetic laso Might be the intelligent scissors tool see: https://docs.gimp.org/2.10/en/gimp-tool-iscissors.html
quick mask For making a selection?
Bottom of the select menu Toggle Quick Mask or shift-Q Toggle-on, paint in white to add a selection, paint black to remove selection. Toggle off. see: https://docs.gimp.org/2.10/en/gimp-image...utton.html
but...there are also layer masks which are different again. An example here: https://patdavid.net/2011/10/getting-aro...masks.html