Welcome to Android Central! In order to install apps directly to an SD card, the device has to support Adoptable Storage, and LG made the decision not to support it (along with Samsung and I think a few other manufacturers). The reason is that installing apps to SD is risky, since SD cards are inherently less reliable than onboard memory (and read-write speeds are slower, thus impacting performance).
SD cards have always been best used for storage of individual files, like media files and documents. If you want to install more apps than you can now, then you need to look into a phone with more than 32 GB of internal storage. Even most midrange phones come with at least 64 GB of internal storage nowadays.