Many triangle centers, as listed in ETC, offer links to sketches of various types.
Some of them are described here.

#### Type 1 GeoGebra (.ggb)

These dynamic sketches can be opened by GeoGebra Classic 6. A free download of this highly recommended resource for creating, experimenting, and discovering, is available at THIS SITE. (There are several options; be sure to choose GeoGebra Classic 6.)

Examples of ggb sketchs in ETC: X(1)-X(29) and many others.

#### Type 2. The Geometer's Sketchpad (.gsp)

These sketches can be opened by The Geometer's Sketchpad. Although this program was discontinued in 2020, GSP sketches have been retained in ETC for users who have this software.

Examples of gsp sketchs in ETC: X(1)-X(29) and many others.

#### Type 3. Portable Network Graphics (.png)

These are easy-to manage non-dynamic sketches - just click. Examples in EXP:
X(3): Ellipse associated with the circumcenter
X(3): Hyperbola associated with the circumcenter
X(14): Figure
X(20): "Pythagorean snail"
X(20): Figure
X(57): A construction involving the intouch triangle
X(33602): A construction involving equilateral triangles

#### Type 4. GeoGebra commerical files.

There are non-dynamic sketches hosted by geogebra.org.
Example used at X(33602): Generalization of the first Fermat-Dao-Nhi equilateral triangle

#### Type 5. Videos on YouTube.

Many websites include sketches of triangles with triangle centers. A selection follows:

Wikipedia: "Triangle Center" (includes links to sketches)

Wikipedia: "Modern triangle geometry" (includes links to sketches)

MathWorld: "Incenter" (includes links to sketches)

MathWorld: "Kimberling Center" (includes links to sketches)

Cubics in the Triangle Plane, Bernard Gibert's site, with thousands of intricate sketches involving triangle centers and associated curves. See, for example, K001: Neuberg cubic