One of the basic tenets of typography is the application of a ligature to a particular combination of characters in order to achieve a smoother textural effect to an overall body of text. Common ligatures in hot metal type (letterpress) were fi, fl, ffi, ffl etc. The file attached shows the application of a ligature to an f i combination. See how the dot of the i (the tittle) sits clumsily next to the top of the f whereas the version with the ligatured glyph is much smoother.
Modern digital fonts have multiple ligatures built into the font as individual glyphs and industry standard design software automatically recognizes when a ligature needs to be inserted.
However Squarespace does not automatically substitute ligatures and there appears to be no function in settings to enable you to set this up.
I assume there must be a coding solution to this and if so, how do I apply it as I have no coding experience.