Scales to Play Over D5
Every chord is a subset of several scales: any scale that contains all of a chord's tones fits over it. Pick a chord to see the matching scales from its own root, the major keys the chord belongs to, and full fretboard diagrams for every scale on guitar.
A D5 chord contains the notes D – A. Any scale that includes every one of those 2 tones fits over it — from the root D, that means D Major, D Natural Minor, D Melodic Minor, D Harmonic Minor, D Major Pentatonic, D Minor Pentatonic, D Blues, D Rock 'n' Roll, D Dorian, D Phrygian, D Lydian, D Mixolydian, D Dorian Bebop, D Mixolydian Bebop, D Half Whole Diminished, D Spanish, D Gypsy Major and D Gypsy Minor. Start with the first scale listed: it is the most common choice, and the others color the same chord tones differently.
D5 is also diatonic to 6 major keys: A major (relative minor F#m), A# major (relative minor Gm), C major (relative minor Am), D major (relative minor Bm), F major (relative minor Dm), G major (relative minor Em). In a song from one of those keys you can also solo with the key's own major scale or its relative minor pentatonic across the whole progression, not just this chord.