Are newly added custom fields shown by default?

Yes — once a custom field is created, it is displayed by default on the relevant form. The intent is that adding a field immediately makes it usable for data entry without an extra "enable" step. (Separately, per-user column visibility controls whether a field appears as a column in list/grid views — so users can tailor their own lists — but on the form itself, a new field shows up right…

Yes — once a custom field is created, it is displayed by default on the relevant form. The intent is that adding a field immediately makes it usable for data entry without an extra "enable" step. (Separately, per-user column visibility controls whether a field appears as a column in list/grid views — so users can tailor their own lists — but on the form itself, a new field shows up right away.)