I'm an old man with vision issues, too. Aside from the mods the guys mentioned above, one thing I do to games (Valheim included) is to use graphics filters and adjust the visuals to suit my limitations.
If you have an Nvidia card and use the GeForce Experience overlay, you can run the Game Filter mode. I use to sharpen the image and adjust the color density a little.
If that doesn't work, there are others like Reshade which do the same thing.
These aren't mods, but post-processing injectors that fiddle with the graphics as the game runs. Helps to tweak that smeared look some games have.