How to backup from an USB drive - new Windows 10

Hello,

I got my new Windows 10 laptop today and am currently planning a clean install.
I also need a new backup strategy - I used to use a bootable CD with Acronis TrueImage. This is probably not possible because I no longer have an optical drive. I also wanted to see if there was a free alternative to Arconis.
(Arconis was fast and had a very good compression)

So I wanted to ask you for comments:
Do you know a good free system that can boot from USB - with which you can create a system image of the hard drive or just individual partitions? Best of all on the same USB drive or on a local NAS.
I usually separate the system and the data at partition level and save the data separately anyway.
If possible the image should be mountable.

Macrium Reflect Free.

Is it possible form the Macrium Reflect Bootable USB to CREATE the backup form an whole drive/partition as image.
Or does this only support restoration of the images?

Yes, you can create an image using the rescue drive.