Can I enable both the Internal dynamic page cache and page cache modules?
According to Wim Leers, who is one of the main architects of the caching system in D8.

PUBLISHED on OCTOBER 12, 2015
Drupal 8 now has a Dynamic Page Cache. The Page Cache module only
works for anonymous users, the Dynamic Page Cache module takes that a
step further: it works for any user.
Since April 8, Drupal 8 had its Page Cache enabled by default. Exactly
5 months later, on September 8, the Dynamic Page Cache module was
added to Drupal 8, and also enabled by default.
source: Drupal 8's Dynamic Page Cache

Therefore, both of those caching modules come enabled by default out of the box, you don't have to do anything to enable them.

will not cause any issue?

No issues at all, Drupal 8 was designed to use both.

The Page Cache module caches fully rendered HTML responses — it
assumes only one variant of each response exists, which is only true
for anonymous users. The innovation in 8 on top of 7’s Page Cache is
the addition of cache tags, which allow one to use the Page Cache but
still have instantaneous updates: no more stale content.
The Dynamic Page Cache module caches mostly rendered HTML responses —
because it does not assume only a single variant exists: thanks to
cache contexts, it knows the different variants that exist of each
part of the page, and thus also of the final (fully assembled) page.
During the rendering process, auto-placeholdering ensures that the
parts of the page that are too dynamic to cache or are simply
uncacheable are replaced with placeholders. These placeholders are
only rendered at the very last moment. The Dynamic Page Cache module
caches the page just before those placeholders are replaced.
source: Drupal 8's Dynamic Page Cache