Despite mods that can increase enemy health and stats, they disrupt D&D 5e's balance, and altering the challenge requires smarter AI and a greater number of foes. One can only hope that potential modding tools will allow us to address this issue if they are released at all.
5E's balance is already disrupted by many of Larian's homebrew systems and the the overabundance of way too powerful items. When these things get addressed, you may find the challenge more suited to your tastes.
We also need granular options regarding difficulty rather than having just 3 game modes.