DeletedUser433 Mint doesn't sandbox applications by default, I'm not sure of any mainstream distro that does.
Flatpaks, if you didn't know, are multi-distro application packages that can be installed from an "app-store" like Flathub. These applications are sandboxed to a point but they're not tightly locked down, for example, in terms of files that they can access.
Applications are also distributed by the native package manager (if there is one). On Mint, which is built upon Ubuntu, which is built upon Debian, it's APT. Most of Mint's packages come from the base Ubuntu repository, whilst they also have their own as well for their own packages.
Fedora uses RPM, which is a different manager (akin to APT) with different repos. I've not used Fedora/CentOS/etc for a long time so can't really comment further about it.
For native (rather than Flatpak) applications, it is possible to run them in a sandbox like 'firejail' and you can lock down the files/folders that the application can access. Note though that if you go beyond the default settings, you will need to edit configuration files to add/remove restrictions. Most beginners wouldn't / shouldn't go down this path as it's easy to get something wrong.
Mint also supports 'web-apps' where separate browser profiles are created for the website that you want to visit, allowing for isolation from other websites that are in the main browser. It's not difficult to do this on any other platform either but Mint has a useful GUI to help create them.
As for resource usage, it will depend on how you run your system. However, if you've been running Windows 10 on the same system, then you'll have no problem running any mainstream Linux distro.
As a rule for Linux newcomers, I'd suggest sticking to the distro's own appstore/flatpaks. It is not recommended to go off and install stuff from random (or even well-known) websites. If it's not in the Software Manager, then don't install it or get some community advice before doing so.