Of course, if you are just starting to practice pull-ups, it doesn't matter if your movements are not standard. Anyway, you can practice at both ends. But you'd better work towards the standard movements.
Doing pull-ups can not only thicken biceps, but also make back muscles look good.
2, curved arm barbell practice two heads, curved arm barbell action essentials: generally put down the arm angle of more than 90 degrees, and then pull up the barbell.
Because the arm is fixed by practicing the second head of the barbell, almost all the pull-ups are contributed by your biceps, so this method is very effective.
3, dumbbells practice two heads, there are various methods.