Edits: Parcly Taxel first discovered that the length of cycle cannot be constrained by the 3-connected condition. However, I think
the construction proposed by kabenyuk later is wonderful. Therefore, I
choose it as the best answer. But this does not mean that Parcly
Taxel's construction is not excellent.
A pentagulation is a planar graph whose faces are all of length five; see the following Figure, for example.
My question is:
What is the range of possible values for the length of a cycle in a 3-connected pentagulation?
First, We can find some special values by making some specific observations. For example, $5$-cycles, $8$-cycles, $9$-cycles. But for any integer $i\ge 3$, does there always exist a 3-connected pentagulation that contains a cycle $C_i$?
Note that we can easily see that in any 3-connected planar graph, any two faces can share at most one edge. So the following cases will not occur.
Best Answer
First, how can we construct a 3-connected pentagulation with a large number of vertices. To do this, take the dodecahedral graph and put a new dodecahedral graph inside some face of it. This process can go on as long as you like.
Now consider three cases.
The figure illustrates the cases $k=20,21,22$. Inside each face there is the number of edges of that face included in the cycle.
Addendum.
I find it useful to give another universal reasoning.
Now let's inscribe in each of the three pentagons the dodecahedral graph. Let us call this graph $P$. The graph $P$ is a planar $3$-connected graph.
Another way to partition a triangle into pentagons can be found here (we will call it $Q$). For completeness, here is the $Q$ figure.
Note of February 21. I corrected one inaccuracy in my answer.
One more remark. In point 1 it is actually enough to inscribe the dodecahedral graph into only two of the three pentagons, the result is a graph with $37$ vertices, which is isomorphic to the graph $Q$.