How to apply two animation effects to single text layer?

I would suggest you forget about using the presets for the time being and go back to the basics - read up on what text animators actually are and how they work, then experiment around by manually applying multiple animators and range selectors to understand how they interact. This will be much simpler than trying to figure out how the presets work if you have no prior knowledge.

Mylenium

You can apply as many Text Animation Presets as you want, onto a single Text Layer. However, matters can get quite messy as the different Animation Presets may combine with each other, to the extent where different Animation Presets may cancel each other's intended effect or accentuate each other's effect - the end result is such that you will have a hard time visualizing the actual effect you will be receiving.

To help you out, begin identifying Text Animations as belonging to three different groups —Animating in, Animating out, and Animating while on screen. In fact, the first groups I mentioned are placed into similarly named folders in the main Text Animation Preset folder. Do take note there are other Text Animation Presets that animate either in or out but they have been placed in other folders, for better separation, based on their results they portray.

For your case, you have already alluded to the Florescent Light Preset as an example of an animation that happens on screen. Then you described the Explosion 2 preset as creating a transition out effect. To combine these two, you will want the Florescent Light effect to start first. Then decide where, in time, you want the Explosion 2 preset to begin. You will need to understand that applying presets is identical to pasting keyframes, since most presets include keyframes. When pasting keyframes, it is critical to place your Current Time Indicator (CTI) at the point in time you want the first keyframe to occur, in time. Hence, prior to applying the second preset, first decide on where in time you want the transition out effect to occur, in time. Place the CTI at the decided point in time and and only then should you proceed with applying the preset.

HTH