When expressing a level of certainty or degree of agreement, "to some extent" can be used synonymously with phrases such as "to a certain degree," "partially," "in part," "to a limited extent," and "somewhat." These phrases convey that there is a level of variation in the amount or level of agreement, rather than a clear-cut yes or no answer. Other synonyms include "kind of," "more or less," "sort of," and "partly." It's important to consider the context in which these phrases are used, as some may have a slightly different connotation or level of certainty than others. Regardless, these alternatives allow for a more nuanced and varied expression of opinion or agreement.