"So far as" is a common phrase used to indicate the extent to which something is true or accurate. However, there are several synonyms that can be used in place of this phrase to vary one's expression or writing. These include "to the extent that," "as long as," "insofar as," "as far as," "to the degree that," and "to the limit that." Using these synonyms can make writing more interesting and engaging, especially when used appropriately. It is important to note, however, that the tone and context in which these synonyms are used should be taken into consideration for maximum effectiveness.