It will help us to answer your question if you could provide the exact version number you have installed and details of your operating system e.g. • Windows 10 v1809, MacOS Mojave (10.14) Catalina (10.15) • Adobe Photoshop Version: 20.0.6 20190724.r.80 2019/07/24 You can find this from your application menu: Help >> System Info
The presets above 1:1 are only available in Lightroom Classic. The new cloud version has a maximum of 1:1 but depending on your set-up there may be a work around. For example when I work in the Edit module and zoom to 1:1 I can hold down the ctrl key and zoom greater than 1:1 by using my mouse scroll wheel. Let us know if that works for you.
Scroll should work up/down. To be honest I don’t know the actual pixel level. And it will depend if you have an original or smart preview available. Using the scroll-wheel could be like zooming (stretching) in a browser window. But I find it helpful sometimes e.g. when examining the green or purple fringing to correct chromatic aberration along high contrast edges.