technically speaking in order to render properly on every screen you need 2 different things. first of all you need to set your Orthographic’s camera size to be adapted to the size of the device’s screen and secondly you need to rescale your assets to be adapted to your screen sizes.
as far as the camera concerns. so you need to set the size of the camera’s size to the half of the big side of your current resolution. example:
do that once. Now you can rescale your items and position accordingly to the camera view to have your scene rendered properly in every resolution, this setup requires your pixel to units for all your sprites to be set to 1. if you want to set it to 100 for example you will need to devide the orthographicSize by 100.