Enable custom script on modern SharePoint sites to recover your favourite functionalities
Let me start with a HUGE disclaimer: even though it is possible to enable custom scripts on modern SharePoint, you should only consider using it when there is no other alternative.
Having custom script disabled by default on SharePoint removes functionalities that old school users miss, such as list templates and the solution gallery,among several others. Most of the features removed by custom scripts can be achieved using PnP and SharePoint Online Cmdlets.