When the Galaxy S9 and S9+ debuted last year, TWRP support for Exynos models became available that same day. Things have taken a little longer for the Galaxy S10, but the recovery is now officially available for the Exynos S10+ model. Owners of the regular S10 and the S10e will have to sit tight.
Bear in mind that this is only for Exynos-powered Galaxy S10+ phones — no S10/S10e and no Snapdragon phones, as they often have different kernels and/or device tree blobs. Plus, the devs behind TWRP just can't afford to import all of those international model phones. For what it's worth, even if the Snapdragon model does eventually get a TWRP option, the US models won't be able to use it given that their bootloaders will be firmly locked down.
The TWRP file weighs in at 64.5MB, and it can be downloaded at the source link below. Alternatively, you can use the official TWRP app, also below.
The Galaxy S10 TWRP version is now up as well. This is still only for the Exynos model, and no, this won't work on your S10e.
Official TWRP has arrived for the S10e as well. Again, this is only for the Exynos model.