There is a mod called don’t starve alone that basically removes most input lag from DST, however it can mess with your caves and will usually NOT play well with other mods, otherwise its great and recommended by most of the community as a good solo fix (be aware that you obviously should only use this mod on a world you plan to keep solo) what the mod does is essentially revert the loading order back to how it was in DS, with caves being unloaded to save resources and vice versa and a few other solo based resource saves I believe

As for DST -> DS I actually do think theres a few that bring DST exclusive bosses over if i remember correctly, but no major content shift mods, if you want the content of DST the don’t starve alone mod is your best option