Many archives, both before the COVID pandemic and especially during it, have digitized some of their materials. A great example is the Leo Baeck Institute’s DigiBaeck project, which has digitized almost the entirety of their collections and made them available via Archive.org.
You can check with an archive if some of their materials are digitized, or you can also search through online databases that bring together archives like Yerusha. Oftnetime, an archive’s online catalogue will offer an option to filter for materials which are available digitally.
It is usually easiest to download digitized materials to your own computer, if you are able to, and peruse them as a PDF or equivalent digital file. That way you can browse the materials without relying on the internet connection, and have your own copy of the materials.
Digitized collections can be very useful, but one should also be aware that it is ultimately a selective process. Digitization according to professional standards is time consuming and resource-intensive, and thus very expensive. Some archives only digitize the most important material (or rather, the collections they think are most important).